San y Paes Boa a Hanke Men Ait Reta cert aCe recut ig eh Pee ee " o ne PAu nh ; ign hei i ne CORNELL UNIVERSITY THE Blower Veterinary Library FOUNDED BY ROSWELL P. FLOWER for the use of the N. Y. STATE VETERINARY COLLEGE 1897 Cornell University Library SF 769.K56 y Wi for 1173 vat A text book of veterinar: 3 1924 001 10 ILA A Text Book of Veterinary Pathology A TEXT BOOK VETERINARY PATHOLOGY FOR STUDENTS AND PRACTITIONERS BY A. T. KINSLEY, M. Sc., D. V. S. Pathologist, Kansas City Veterinary College FULLY ILLUSTRATED CHICAGO ALEXANDER EGER 191t Copyrighted at Washington, D. C., by ALEXANDER EGER 1910 LINDEN BROS. PRESS, CHICAGO PRIEFACE, A knowledge of pathology is essential to practitioners and to students of medicine. The general considerations of pathol- ogy, whether in reference to diseases of the human or diseases of domestic animals, are practically identical. Many textbook on this subject are available, but they are especially written fot the practitioner and student of human medicine, and the illus- trations and examples are all in reference to diseases of the human. Such textbooks have been used by the author for sev- eral years in veterinary classes and it was thought that if thy same general pathological principles could be exemplified by cases and illustrations in veterinary medicine, the subject mat ter would be more readily understood by the veterinary student This explains the issuance of the present volume. The writer has endeavored to place every phase of pathol- ogy from the veterinarian’s point of view. The entire subject matter has been expressed as far as possible in common every: day language, with the hope that all readers will have no trou- ble in grasping the pathologie facts. An extensive glossary has been appended and will be of considerable aid because practi- cally every technical term, with its analysis and definition, will be found therein. The author is greatly indebted to Dr. S. Stewart, Dean of the Kansas City Veterinary College; Dr. D. M. Campbell, edi- tor of The American Journal of Veterinary Medicine; Prof. W. E. King, Bacteriologist of the Kansas State Agricultural College; Dr. F. J. Hall, Chief of the Food Inspection Department Kan- sas City, Mo., and formerly pathologist of the Medical Depart- ment University of Kansas; Dr. L. Rosenwald, formerly patholo- gist of the Kansas City Veterinary College; Dr. Geo. F. Babb, Milk Inspector of the city of Topeka, Kansas; Dr. D. Cham- plain, editor of The Milk-Man, for suggestions made by them concerning the text matter. Also Dr. R. F. Bourne, physiologist of the Kansas City Veterinary College; Dr. C. D. Folse, City Milk and Meat Inspector of Marshall, Texas, and Mr. Chas. Sals- bery, microscopic laboratory assistant in the Kansas City Vet- erinary College, for their assistance in the preparation of the illustrations. The author consulted various text-books, journals and other publications while preparing the text for which acknowledge- ment is hereby made. If this book supplies the practitioner and the student of veterinary medicine with clear, concise statements of veterinary thology, the purpose of the book has been fulfilled. _ 2 A. T. K. CONTENTS. EPG ACG. eae war cen uteretiaaie cg aut eee ena ananen een peal, ae CHAPTER I. PO EOUEICHS: ary yc aise auediy ss viele as ew ee wR R aE RE 19 ee ect cee gateneen see tarde Ait tN we aie ar nde 20 CHAPTER II. General Consideration of Disease ...................04. 34 able of Vegetable Parasites 2. ..cc«va censuses a cass 48 SRECHATIIN OSS qiuasedi cs ovis sal ee ek bended wae bes 51 MCHIZOMNCELC Seen iam ease che men item eh ol 52 Ampimial Parasites? au wos CNS oan deer eras epee 62 PT OLOZ Oars taco cee a er aos tong a eae rlat ie) 63 ebelmuinthes:. raj wers nd hvala oa Seed closcmsacnoni a cueace 63 AaTeHROpOd ay Shae tacrsetttasaesa ee eae Nee eset he cee 69 CHAPTER III TMMUN yeeros caves ee Geont ene epee waar Mene 78 CHAPTER IV Malformations: si riccc iA lenstess, cat saeeterat ele stow planeeanatne (eetiele wanes 92 CHAPTER V. Circulatory Disturbalices: 2.nsccs ees devnet eels eves Rees oe 110 Hemorrhage: saan seieqertte cru eee men Caer eee 112 Leyva puOr rHagidicd sits ao oki ser weeart Geta ohne a achare ac 117 Oedema, Dropsy or Hydrops .................00.. 118 ‘Prom bOStS: waviness bu ered oe eho eet ae eee 122 FamiboOlisin) 144 asid.g-0r acssop oot ton aes ae awe aes 128 TSC He Tiara ihe crarecce tess serie Gua ace esa oceay as See kes 132 By peréemia. (Bassive) ..ces sous aerdeeeraenh de x 133 Fy peremia: (Active): 4.4446.245 ose eb eee 135 CHAPTER VI. Inflammation; 2424ee 5 ee iiok eae Ree een 138 CHAPTER VII. Progressive Tisstie Changes ......0:+4:4ssesssenesterees 177 PREG OHETAINOM. esc ire pa roen eee ad Macnee ae ernie 177 ii CONTENTS. , PAGE Wiound healing. ai suuce een: stheteuiate camatcg uve veer ccs 183 Ely PerErO Dy? sa austac hd ih uci serene teaetnees saeerase a 188 EDEL DIAST AY . csp iteece teste uote see cecends can thoretete gue eceemerauat as 191 Weta pla stad ccc altin tera anette ee eae 193 CHAPTER VIII. Retrogressive Tissue Changes .............-0 eee e cetera 195. INET ODI Ye hssecs os siete stash leer raed casee tages Gres 196 Cloudy Swelling 2 2ncvesas ccakead core aes sae 200 Patty Chane@es 220s cutee wel en eer wee 203 Aatiby LO1d SCN ATS CS oases x anc as sia nig Ska sata ecm RC RTE R Cats 210 Eisai: CHANG es: -j2 sci tists shen teen a eae BSNS 212 Murcoid Changes) s¢:ccpains cet aer ened etre eet 214 Goliad’ sGhanGess mgcess- ence Cee raw srarigieie a ote te ete 217 Serous: Iihltra tion .2cceigon Sete ene 220 Glycogenre Infiltration: 23 cose. eee eerie 221 Usratietolmnittl trations. seats ce atery aetna aornea nina ty es 223 INGEAPOSIS! cas Sh onaustrle hes ah tdi ron eee 224 COSSUMCALTOM oat eae scree ios n She canta cia) we oeeaneacomtal erties 226. Calcareous Imhltration oo si .uk Heat a eee ares 227 Galeu li aeethene eee nen ae he eee ene MAS 230 (COMER eMEM tS: davai teenie ten ete atta ak Quo eases 23 Pignientarny Canes, seins hacer. ecotcninintivoy keh Cmts 241 EXCESSIVE BISITENtALION, s.jr-ciiieeaiewiecieads base telsials 243 Absence of, or Diminished Pigmentation........... 249 CHAPTER IX. Necrosisiiand (Death: .saucc. see eed aces cect anes nees ses 251-262 Phystolocic Death 4 vives a cetien ware ee Oe 262 PathOloeie Gath sid dats paca Momeasie Wa stare aim alies 263 CHAPTER X. CR UIIOT SA reas mtorr concen eeiee sa en ets Me manor arama See chor mies coer 267 Fi DRG IAT EIN wah saeses eck avon esas teh achipe ees eet nce ee eA taS 278 IBS OTM ERAS 5 Seennal oiled at show cts chaah Ae: ava copeecmionbotande apt be 282 (Soiled ac irda anetes eee uetae Rete tase eres vee eaten Aa ened eS fae 2838 (SUE O I ain tien a meavarar tse arerass ars, bytecney Tse tie tswos din erase wa ay ase 288 (GING Iara ieee Stet oat cten eer Aah at Sela aka 289 CAO HT Oineteh eats Snes Sain tees teas ered tee enn ce ane 289 INGUIRO MITES. acts der aden oeuvre Senge amas Dele ee earns: 293 HTML TAMA) 9g Sore ahr Stee ysl aon ONIN aANa par cttrla ce BASE arch rh eres 293 Myotis sath ee tsatie a aan e uate Seatac nas gee enenters Nese Se 296 Sali GOT aye a Ree ee eh ae eel ein a aca tae aa 298 CONTENTS. ill 7 . PAGE EPG Sy ireteergirgealtancntep nse ad aiieaen i 2 an eeone eae 318 Embryonic Epithelial Tumorg occ cic in oween vee ccce ede SE ater erase pate dc seats ae eg 331 ASIAN OMA Naabs es wvetier ne So oeta och Bae Aiea tn heed eee tice 332 CYS Lome coh ee ce ees ery Set eee ance edt asa R ry US 335 CHAPTER XI. FESO ease es ce erat eee aR nas tc een Rel epg athens 339 CHAPTER XII. Infective: -Granulomata. owes chs cukinsd coumentereeres 344 MLUIDERCUIOSIS! jutaic mG naire, ear aden ra dead ia 344 ANCHIMOTIY COSTS Acre yistcnin eG casio A Oey Bn eet 345 Glanders: 2octtentneetiene v abe Peete daeaae 361 Epithelioma Contagiosum si..s4 yeneus vevavswunes & 371 Glossary sivee os suerte eter ate tie aon ERR Ries ene seats 373 LIST OF INSERTS. Insert I—Botanical Names ..........+.... Next to page 45 Insert’ I]—Bacteria sc.ccacceiveae actives ren Next to page 62 Insert: [IP rotezoan4 vas eine ote ha ees Next to page 63 Insert PV Helminths: on scctuncccaca sees ail Next to page 66 Insert VYV—Arthropoda 22. nce. eee e eee Next to page 71 A LIST OF THE ILLUSTRATIONS. FIGURE PAGE I—Diagram of a Eypica le Gell ls. so tansswstacs rape oceans fotica atte migmenanne aie ioe 21 2) 3 =AMILOSIS: eat te eae Dee Ae ewe OOS See ome esse Reames 25 ASD ivasiOne EA NUGTE Sic ond savgnes gue rcsara: ces-srexecouenere erode ailesereseveus aacovaue chewed Qlare 26 E— Division Ot Gell tate cere Aieeana wai e ee arele aie iaeatto eek emerancaae amen 26 6—Cell in Resting Stage.....seeeeeeeseceee Waka wages sennie head: 27 7—Prophase, Showing Division of Centrosome......+++seeeeeeee eens 2 8—Prophase, Showing Separation of Centrosomes.....-.+e+eeeeeeees 27 Oe Lap ase rita sea siesta tive Se sess tas a Se same Sete EN STEN 27 10, Il 12, 13—Indirect Cell Division— ‘Metaphase. Anaphase, Telophase 28 14—Ciliated Epithelium, Tracheas:+s Paella MEMIMOCOCCUS: “iiaaurnewe Kids nteonmblga Ina aie iseen aoe 66 36 Talenia SOlUM sessyeaeneies Owe cer vows demu auria ean suelace uswiece deorgnens 67 37 Ot TO Gayl US oa MI CEUT LIS v1 se: Secs tov te Sound avg avoae ab sega Baxi o wana bmee Wee ok 67 88-—Stronewitis: Paradox us) .<:o-.sksien hice oalaaetnahrn ewe ea eionloe buen. 68 9SHilaria. Papillosar aannuwissiee nape eae & ciles. cecdercaven vein aareane 68 A SORYUPIS Gury Wl ais sis. ieiesnasdes ene susvsse, Neve we herstnaeee aa wielne Heels aes 690 4i—Syngamus: “Urachealis: wscwesien sacestery saeina ae Movavi nssvesnsiwioune: 70 42-—Scletostoma:, ELypostomitim iss elec wa sros sa cnareuirss awe andtnateeieesc, 70 43—Trichocephalus: Depressiusculus, LymphosSarcoma. Elearts as ais cmaccequne perein Meaerramnannenen 302 1598 —Lympho-Sarcoma:. ss.0 sine nave tnce ste ene iene kat ee se RS 303 Iso=— Spindle ‘Cell, Sar€oma: Mitilles vusc.stos eek w robe Aoteta 4 aden tates Hane 304 1T6o==Spindle “Gellin Sarcotna: cucy cava .aciesecla veo ew asda mednete we ane ek ctoA 305 161—=Myeélord er ‘Giant’ Cell: Sarcoma, <-.cle.c0eeei ac vicked aaoesatna carpets bane 306 T62—Mixeéd: Cell ‘Sarcoma, HOrse acs tate ede aa bia aot Ad aeo aes 307 163——Mixédi Gell Sarcoma, Jaws ssmisncies i cea gs es eccenr cane th beende 308 164=Mixed: Cell” Sarcoma: .4 vy. cseeen cue doors sage ee Beeld 309 165—Alveolar SAT GOTT -amiervis e scaincea eh Acerolsl dea wes Debit adelante gundevigies mms ateinansnrees 322 6—Epithelioma, Microscopic «+..0¢s+s200esneaeccneenereeens cde etes 323 177—Epithelioma, Microscopic «++... es see eee eee eee eter eee eee 324. 178—Epithelioma, Pearl Cell eee eee ee eee eee eee cent tenes 25 179—Adenoma, Mammae ..---- +e ere eee reece tenet eee eens 326 t8o—Adenoma, Microscopic ..--.. eee cece eter cece ete tte tee eee 32 181—Adeno-Sarcoma, Microscopic ..----+eeeee eee reece eee eee ees 328 T82—Cystadenoma .-- eee er ee cree creer cere rere eens e eect e eens 320 183—Hypernephroma ..eeeee cece eee e eee eee eee eect e ett eens 330 184—Dermoid Cyst delet tea tes Fl sahacos ea ae cuse tara ahaan ny onesie Sioa he UNG Lie sear es hareeties 332 18s—Dermoid Cyst, Eye sss eee ce creer rete etree teen ete etree 333 186—Dentigerous Cyst gee ahes acre Sy aN at Re wan ated eae ayaa aS Cacao oO a Sao nc sot Pe agrees 334 187—Cyst, Dog Neck ..-+eeeeeeeee eee eter eee eee eee e eee e eee 336 188—Uterine Cyst ..ceceeecee cece cece teen eee enn t tenn ete e ences 337 vill LIST OF ILLUSTRATIONS. FIGURE PAGE LEGS PENGr=— Crisis aiid: LayS1s~ ay sus. n yee denanhaanisred Mucuewuelaamee 340 1O07—COntinuOus, Hever ice nae emia nels niemwn ca peee pepe ein ame ies 342 IOI Reitithent FP eVer Cae Ve sec ace eeor ss aise. avcvsyletesed a ahentaased whe as dnacs PERE 342 192—liitermittent: Pever, (Gurve) <1 cdcccvesanssame paaeg deen ae careu dane 343 103—Bacterium Tuberculosis; Bovine esos peeisdenavevorssecveuease 345 194—Small Cellular Tubércular Liver .....c0..00n seeps scence ne veya 348 165 Luberculosis: Wesion, Tater: .xcacoosdanwvmacos densa scan Seow aimee 350 196—Tuberculosis Mammary Gland ins. sevsecene cde cache cueens Famake 351 1O7= Ray PUSS: CACHHOMYCES ssi marstcenedenedetnsuneoe bende, sams SUE 356 T6S—=Actinomycotic: Tonewe: nc raovgaccacesce peat sasa oe asad 359 TOO Bacillus. MAME sacuiscuraknde creda ene iseu sn gee. eda eeaacesess 362 260-—Glanders: Wsesion: Bary 2 caneh scare ted wicerin tai akg Gi aacetechonsens ate Ade aes 365 2oi—glanders, Nasal Wee acs toaceenas ecdou Saane eben eeaeua een aeae re 366 202—Glanders:. Microscopie: saugncswasaeencdetcage dees teased eee oes 307 203 E pithelionia, (ContaeiOstainiy. Za fekdunie tetas axasovauayss sduesel ors e gueermereeenokere 369 204—Epithelioinia, -GontagiOsuti: «acecc owe desu sass aden ap alan Moen ee 370 205—Epithelioma, Contagiosum, Microscopic ..... se... eee ee eee eee 371 CHAPTER I. DEFINITIONS. Pathology is the science of disease. It is the science which treats of the nature, causes, progress, symptoms and termina- tion or result of disease. It includes etiology, i. e., the study of the causes of disease, and pathogenesis, that is, the study of the course, abnormal functions and lesions produced in disease. General Pathology is confined to the explanation of the sum- mary of the facts obtained in the study of special pathology. It is concerned essentially in the solution of general principles of those morbid conditions that are common to the entire organism, as malformation, degeneration, regeneration, inflammation, neo- formation and fever. Special Pathology deals with all the abnormalities or diseased conditions of one part or organ as the diseases of the ear, skin, etc., and consequently special pathology 1s further subdivided into otologic pathology, dermatologic pathology, ete. Pathologic Physiology, is that part of pathology which has to do with the investigation and description of abnormal functions of a diseased organ or animal. The pathologic physiology is, in many cases, the principle symptom of a disease, e. g., paraly- sis of the radial nerve. Abnormal function is frequently the only evidence discernible in a disease, e. g., epilepsy. Pathologic Anatomy, or morbid anatomy, is concerned in the structural changes in a diseased tissue or organ. Pathologic changes in the structure of a tissue or organ are collectively termed lesions. Lesions may be sufficiently gross that they are readily observed with the unaided eye or they may be so min- ute that the miscroscope is necessary for their detection. The investigation and the recording of facts observed in the study of gross and minute lesions are included in gross, or macroscopic pathologic anatomy and minute, or microscopic pathologic an- atomy respectively. Human Pathology has to do with the facts observed in the study of the diseases of the human. Comparative Pathology, is the name applied to the study of the diseases of all animals in which the diseases of one genus, (group of animals) is taken as a standard and the diseases of all other animals are discussed in comparison with the type selected. Veterinary Pathology, is a discourse on the diseases of domestic animals, 19 20 VETERINARY PATHOLOGY. THE CELL. ANATOMIC. Structure. Body. Nucleus, Centrosome. Membrane, Shape. Size. PHYSIOLOGIC. Growth, Reproduction, Motion. Metabolism, Anabolism. Katabolism. IRRITABILITY. Structurally, an animal body is composed of definitely ar- ranged parts, called organs. An organ is a portion of the body having a particular function and is, structurally, a tissue-complex in which each tissue has a certain definite proportion and relation. A tissue is composed of like or similar cells with more or less intercellular substance interposed. The intercellular substance is usually a product of the cells. A cell has been defined as a microscopic mass of protoplasm containing sufficient individ- uality to possess a life history. The function of an animal body is the sum total of the corre- lated functions of its component tissues. The function of a tissue is the sum total of the function of its cells. Thus a cell represents the anatomical or structural unit and the physiologic or functional unit of all animal bodies. In ancient times disease was thought to be the result of the entrance into the body of some “evil spirit,” and the symp- toms presented during disease was evidence of the struggle beween the body and the “evil spirit.” During the middle ages, Hippocrates, “The Father of Medicine,” established the Hippo- cratic Theory of disease. Hippocrates taught, Ist, that the body was composed of four humors, viz., blood, phlegm, yellow bile and black bile; 2nd, that health consisted of the proper balance of the humors; and 3d, that disturbed proportions of the hum- ors resulted in disease. Modern pathology is based upon the knowledge of cell activi- ties. Virchow was the father of cellular pathology. He first taught the cellular theory to students of pathology and he first advocated it in published articles. Cellular physiology was really an outgrowth of cellular pathology. A knowledge of cells is THE. CELL; ?1 indispensable in the study of pathology and a brief description is here appended. Structure—Cells are variable in structure. The active consti- tuent of all animal cells is protoplasmic in nature. The essen- tial parts of animal cells are the cell-body, nucleus and centro- some. The cell-body is present in pratically all cells. It is com- posed of semisolid protoplasm, a portion of which is of a stringy BOhm- David off- Huber. 1—Diagram of a Typical Cell, after Fig. 1. Vacuoles. sS. Centrosome. 2. Cell-membrane. 9. Foreign inclosures. 3. Exoplasm. 10. Hyaloplasm. 4. Nuclear membrane. 11. Spongioplasm. 6. Nucleolus. 12, Chromatin network. 6. Chromatin net-knot 13. Linin network. 7. Centrosphere. 14. Nucleoplasm. consistency and is termed spongioplasm. In the meshes of the spongioplasm there is found a fluid protoplasm, designated hya- loplasm. The relative proportion of spongioplasm and hyalo- 22 VETERINARY PATHOLOGY. plasm varies in different cells and even in different parts ol the same cell. Particles of food and various other insoluble sub- stances are not uncommon in the cell body. Vacuoles are fre- quently observed, especially in wandering cells. The nucleus is constant in all functioning or active cells except the mammalian red blood corpuscles, and some of the pulmonary alveolar epithelial cells. The nucleus appears as a dense body and is usually centrally located in the cell body. The relative proportion of nucleus to cell body is inconstant, e. g., the lymphocyte is practically all nucleus; some epithelial cells have a very small nucleus and a very large cell body. The nucleus varies in shape from a sphere to an irregular mass, and is sur- rounded by an incomplete membrane. The essential structure of the nucleus is a chromatin network. The spongioplasm and hyaloplasm of the cell body are continuous through the incomplete nuclear membrane into the nucleus where they are designated linin and nucleoplasm respectively. The nucleus may also contain a nucleolus which is probably a knot in the chro- matin network. The centrosome is a dense refractile body found in the nucleus or in the cell body just outside the nuclear membrane. Many fine radiating fibres may extend outward from the centro- some. A cell membrane may or may not be present. This mem- braae is formed by a condensation of the substance of the cell body. The sarcolemma of a muscle fibre is perhaps the most typical cell membrane found in animal cells, the red corpuscle has a modified cell membrane. A nerve cell possesses a neuri- lemma, although it is probably not a true cell membrane. Shape.—Embryonic cells are usualiy spherical in shape and it is probable that sphericity is a primitive quality of cells. The shape of matured cells is determined by their function and loca- tion. External surface cells are usually flat and when subject to pressure and friction they are arranged in strata, i. e., they are stratified. The cells lining the air vesicles are flat because of the necessity of the exchange of gases through them. Muscle cells are elongated to allow of contraction to produce motion. Goblet cells are large and more or less spherical because of the elaboration of mucus in them. Accommodation to space pro- duces variation in the shape of cells, thus; fat cells are originally spherical, but because of pressure, they become polyhedral. Cells vary from the flat pavemental cells to those spherical in shape. Pressure is probably the most important factor in the produc- THE CELL. 25 tion of pathologic variation in cell morphology. Thus parenchym- atous cells, as hepatic and renal cells, frequently become com- pressed by hyperplastic interstitial tissue sufficiently to change their shape from polygonal or cuboidal to irregularly flattened or fusiform. Columns of tumor cells may become pressed suffi- ciently by the invaded tissue to produce scale like cells or the so- called pearl cells. On the other hand, the same variety of tumor cells developed in tissue in which mutual pressure is limited, assume sphericity. Size.—Cells vary in size from the lymphoid cells that are from 4 to 8 microns in diameter to the marrow cells that are from 30 to 60 microns in diameter. The size of the cell is characteristic of the tissue they compose. Equalization of the surface and mass is a factor in the determination of the size of cells. Function of cells also has some bearing upon their size; thus, cells that have the power of independent motion and rap- idly acting cells are usually small. Food is no doubt a deter- mining factor in the size of cells. Ova are large because of the storage of food. Pathologie variation in the size of cells is of common occur- rence. Hypertrophy is the abnormal enlargement of individual cells. The size of red blood cells is variable in pernicious ane- mia, (swamp fever), of the horse. Several cells may fuse, forming a cell-complex, syncytium, or giant cell in and arouna foreign bodies, and in tubercular and actinomycotic lesions. Growth.—Growth in cells is the exercise of that property or function which results in their enlargement or it is the process by which thev are increased in size. That cells do grow is self- evident and is common knowledge. A central, polymeric pro- tein-molecule is supposed to be the essential structure of all active cells. This central, polymeric molecule is probably unsat- urated and new simple molecules may be serially combined with it and then the cell becomes larger and grows. This prop- erty of cells is especially evident during the embryonic period but gradually diminishes to the time of maturity, when it is largely supplanted by other functions. The growth of ceils is accompanied by the accummulation of energy. The larger a cell, other things being equal, the greater the potential energy. All functioning of cells, except growth, is accompanied by the liberation of energy. Growth results in accummulation of poten- tial energy and other functions convert potential into kinetic energy, though both types of energy may be produced simultane- ously and may be interdependent; thus the growth of muscle is 24 VETERINARY PATILOLOGY. dependent upon frequent and appropriate exercise (liberation of kinetic energy ). Growth within the normal cell is dependent upon inherited tendencies and a sufficient supply of nutrition. Other functions, as motion, are apparently entirely governed by environmental stimuli plus the required nutrition. The growth of cells con- tinues until they, and the part they compose, become of such a size that the economic relation of surface and mass becomes disproportionate. The disproportionate relation of surface to mass is corrected by rapid cell division or cell dissociation. In either case the total cell surface is increased. According to Harris, “Physiologic inertia” is of considerable importance in growth of cells. When a cell is stimulated to action, the action does not cease immediately when the stimulus is removed or suspended. Thus when a cell starts to grow, it tends to grow continually because of the “physiologic inertia.”” Abnormal varia- tion in cell growth is characteristic of hypertrophy. Reproduction.—Cell reproduction is the process by which the number of cells is increased. The ultimate outcome of cell reproduction and cell growth, is to increase the mass or volume. Cell reproduction is not distinct and separable from cell growth, in fact growth always precedes division. Reproduction is one means of regulating the relation of surface to mass. Two types of normal cell reproduction have been described by cytologists. These methods are amitosis, (direct cell division), and mitosis, (indirect cell division.) 1. DIRECT CELL DIVISION, AMITOSIS, is simple cell division in which the nucleus and cell body divide without any previous nuclear changes. This type of cell reproduction or division is normal in some lower forms of life and possibly in some embry- onic tissues of higher animals. However, it is not very common in normal adult tissues of higher animals. The polynuclear leucocytes occasionally reproduce by amitosis; endothelial cells are also thought to reproduce in the same way. It is possible that cells of any tissue may multiply by amitosis. Cells repro- duced hy amitotic division are considered abnormal by most investigators. Direct cell division is especially evidenced in rapidly growine tumors, chronic inflammatory areas, leukemic tissue and many other pathologie conditions. The process is briefly as follows: There are one or more depressions in the nucleus which gradually extend until the nucleus is divided into two or more parts, (this is the origin of polynuclear cells: possi- bly it may also account for the giant cells), After, the nucleus THE CELL. 25 has divided, each part migrates to a different part of the cell body and the cell body is so divided that one or more nuclei are found in each segment. Thus the process is completed. In some instances, one or even two centrosomes may be present. Fig. 2.—Amitosis, showing division of the nucleolus. 2. INDIRECT CELL DIVISION, MITOSIS, OR KARYOKINESIS, is the usual mode of cell reproduction. The frequency and intricacy ol this complicated process is indicative of the exactness of nature’s methods. An equal division of the nucleus, or more specifically Fig. 3.—Amitosis. showing migration of the nucleoli to opposite voles of the nucleus, of the nuclear chromatin, is apparently the object of this type of reproduction. It is more delicate and exact than direct cell division. The following four stages are recognized in indirect cell division, but they are not separate and distinct. 26 VETERINARY PATHOLOGY. A. Prophase. This is the preparatory stage. The nuclear chromatin which, in the resting cell, is an irregularly arranged net-work, becomes a continuous single thread, forming the so- Fig. 4—Division of nucleus called spirem or loose skein. The chromatin thread divides into a definite and even number of segments, (the number varying in different animals, but always constant in the same species) known as chromosomes. These chromosomes are equal in length | Be Fig. 5.—Division of cell. and are usually bent like the letter “u.” The chromosomes are radially assembled around the central point in the nucleus, thus forming the monaster or single star. The nuclear membrane becomes less and less distinct as the spirem is forming and fin- ally disappears. As the nuclear changes are progressing, a centrosome becomes prominent either within the nucleus or in the cell body just outside the nuclear membrane. The centro- THE CELL. 27 some divides, the daughter centrosomes separate and wander to opposite sides of the nucleus. Radiating lines, known as mantle fibres, appear and extend from each centrosome to the chromo- somes. Fig. 6. Fig. 7. Fig. 6.—Cell in resting stage. lig. 7.—Prophase showing division of centrosome. B. Metaphase. During this stage the chromosomes are split or cleaved longtitudinally into daughter chromosomes apparently by the traction of the mantle fibres of the centro- somes. Fig. 9. Fig. 8. Fig, 8.—Prophase showing separation of centrosomes. Fig. 9.—Metaphase. 28 VETERINARY PATHOLOGY. C. clnaphase. The daughter chromosomes are attracted along the mantle fibres until they reach the centrosomes around which they are ultimately assembled, forming an aster OT star at either pole. This particular portion of the anaphase 1s designated the diaster or double star. There is also evidence of transverse indentation of the cell body near the median line. Fig. 10. Fig. 11. Fig. 10.—Metaphase. Fig. 11.—Anaphase. D. Telophase. The nuclear changes during this phase are practically the reverse of those occurring in the prophase, i. e., the chromosomes fuse forming a chromatin thread which later forms the chromatin network. The nuclear membrane appears and the centrosome loses its mantle fibres and may even entirely disappear. The cell body is completely divided by invagination from the margins, and then the daughter cells are completed and assume the appearance of their ancestors. Rig. 12. Fig. 13. Fig 12.—Anaphase. Fis. 13.—Telophase. THE CELL. 29 Morbid cell reproduction is especially evident in neoplasms and in hyperplastic formation. The type of reproduction in neo- plasms is variable, being normal or modified, direct or indirect. Indirect division is of most frequent occurrence in hyperplasia, the rapidity of multiplication being the only apparent difference from that occurring in normal reproduction. All variations of division occur in tumors. Motion.—Motility is that property of a cell which refers either to the intracellular movement of its parts, the position of the cell as a whole remaining fixed, or it signifies the inde- pendent movement of the cell. All movement is dependent <" roe \o go Fig. 14.—Ciliated Epithelium, Trachea, upon activity of the cell protoplasm. The cells of specialized tissues, except blood, are fixed i. e. not motile. Intracellular movement is due to the circulation or stream- ing of the protoplasm from one portion of the cell to another. This type of movement may become so extensive that the shape of the cell will be changed. It is common in the cells of lower forms of life as well as in some of the cells of higher animals. The specific cause of the intracellular protoplasmic circulation has never been positively determined but it 1s probably the result of a disturbed chemic equilibrium of the cell margins and their 30 VETERINARY PATHOLOGY, surroundings. Leucocytic amoeboid movement is due to intra- cellular protoplasmic circulation. Leucocytic immigration prob- ably is the result of chemic attraction, (positive chemotaxis), which stimulates the circulating protoplasm within the cell to constantly flow toward the point of greatest chemical affinity and finally the cell reaches that point. Leucocytic emigration is based upon the same principal except that the chemic in- ea ye? Soo thal Silay! « laid 1 Tat. 2. Horse, Fig. 15.—Spermatozoa, THE CELL. 3l fluence is negative, (negative chemotaxis), and the cell 1s forced away from the center of the disturbed chemic equilibrium. Ciliary movement is the wave like motion of small hair like protoplasmic projections of cells known as cilia. Ciliary motion occurring in migrating or wandering cells produces movement of the entire cell and in stationary cells, produces move- ment of fluids or semifluids that contact the cilia. In higher animals motion of entire cells as a result of ciliary movement is observed only in spermatozoa. The normal function of ciliary movement is to aid in propelling mucus in the respiratory tract, ova in the Fallopian tubes, spermatozoa in the vas deferens, etc. Ciliary movement is due to intracellular protoplasmic disturb- ances, at least it is the result of chemic influences. Over stimu- lation or disease may produce increased action and finally fatigue or paralysis of the cilia, or they may produce cessation of their action. The most extensive and important cell movement is noted in the highly specialized muscular cell. As the muscle cell maintains its relative position when contraction takes place, the movement is principally evident in the structures to which the muscle fibre is attached. The rate and extent of contraction vary in the different varieties of muscle. The spongioplasm is the active portion of the cell in contraction, the hyaloplasm being passive only in function. Nerve fibres terminate in end-organs, i. e., muscle plates, through which are transmitted impulses that produce muscular contraction. Muscular movement is an in- dispensable function, as circulation and respiration are abso- lutely dependent upon it. Digestion and urination would also be suspended if muscular action were curtailed. Immobility may be the result of muscular fatigue or dissociation of motor nerves and muscle fibres, or be due to neuroses. Muscular spasms are usually the result of violent stimulation of the motor nerves, although it may result from excessive stimulation of the muscle fibres themselves. Metabolism.—Metabolism is a term used to designate the processes included in nutrition or digestion, absorption, assimila- tion, katabolism, and excretion. These processes are the results of cell action. Metabolism includes two general processes, i. e., constructive metabolism or anabolism and destructive metabol- ism or katabolism. Active cells are constantly consuming foods and eliminating waste material. The quantity, quality and previous preparation of the nutritive substances required, varies according to the specialization and degree of action of cells. The leucocyte is relatively simple, i. e., it is a primitive type of cell. ‘A leucocyte is not very selective in its food requirements. It 32 VETERINARY PATHOLOGY. produces ferments that digest food substances, as well as necro- tic tissue as inflammatory exudate. The phagocytic action of leucocytes is largely dependent upon the fact that the substances phagocytized have been previously rendered inert. Connective tissue cells are closely related to leucocytes in their power of producing digestive ferments. Endothelial cells produce fer- ments which aided by the leucocytic ferment, dissolve and devour thrombi and emboli. On the cther hand nerve cells are quite selective in their food requirements and they have practically no power of producing digestive ferments. The foods required by cells are nitrogenous and non-nitro- genous. Nitrogenous nutrients are used in the construction and maintainance of the cell protoplasm. The non-nitrogenous foods are essentially carbohydrates and fats which are consumed when energy, in the form of either heat or motion, is liberated. When non-nitrogenous foods are consumed in excess, some of them ma;; be stored as glycogen in the liver, or as fat in the various parts of the body, thus producing glycogenic or fatty in- filtration. The consumption of nitrogenous food in excess may result in overwork of nitrogenous excretory organs as in induced albuminuria. Insufficient supply of carbonaceous food produces disturbed metabolism, because of the necessary conversion of nitrogenous food or nitrogenous cell constituents into carbon- aceous substances, in order that the body energy may be main- tained. Diminished supply of nitrogenous foods is temporarily compensated for by consumption of the protoplasm of the body cells. If the nitrogenous food supply is materially diminished for a long time or entirely withheld, the body cells atrophy, degenerate, and ultimately die. The waste products are also divisible into two classes, nitro- genous and non-nitrogenous. The nitrogenous waste substances are urea, or some allied product. They represent katabolic pro- ducts, 1. e., the results of destructive changes in the cell proto- plasm. The carbohydrates and fats are almost entirely converted into energy ; carbon dioxide and water being the chief katabolic products. Irritability —Irritability is the property of certain cells which enables them to respond to stimuli. Stimuli may be chemie, thermic, electric or mechanic. The property of irritability is vested especially in nerve cells, although other cells are slightly irritable, e. g., muscle cells. The degree of sensitiveness varies greatly in different species of animals and to a less extent in dif- ferent individuals of the same species. Thus the thoroughbred horse has a more sensitive skin than the draft horse. Irritability THE CELL. 33 is a very important property because it is the means through which the nature of environments is recognized. Many of the ac- tivities of the body are responses to impulses resulting from stim- ulation of irritable cells. Irritability is the property of cells which enables an animal to communicate with its environments as, sight hearing, smell, etc. Irritability may be intensified or diminished by pathological processes. Thus chemic variations, resulting from katabolism in tissues affected with inflammation, produce increased irritability or intensify stimulation of nerves, and is manifested by hyperasthesia or by pain. Anemic and venous hyperemic tissues are usually less sensitive than normal tissues because of the accumulation of waste product that tend to inhibit impulses or diminish irritability. Correlation of the cell to the entire organ is of considerable moment, and is de- pendent upon irritability and response to stimuli. CHAPTER II. GENERAL CONSIDERATION OF DISEASE. DEFINITION. CLASSIFICATION as to, Time affected. Inherited. Definition. Predisposition. Tumors, Neuroses. Malformationus—not rare.. Infections—rarely if ever. elcquired, Definition. Antenatal—(congenital)—Exanthema., Postnal—Spavin. Extent in atfected animals, Local—inflamimation, General—anthrax. ETIOLOGY. Predisposing. Heredity—Epiplepsy. Inbreeding—General debility. lge—Canine and colt distemper, blackleg. Sexr—Males urethral calculi; females, peritonitis, Genus—Hogs, cholera; cattle, blackleg. Breed—Clydesdale, laminitis; jersey tuberculosis. Color—IVhite animals, sunburn. Location—Pica. Climate—Coutracted hoofs. Season—Pueumonia, insolation. Food and |Vater—Indigestion. Occupation—City horses, foot disease; dairy cow, udder disease. Effects of previous disease—Purpura hemorrhagica. Exciting. Mechanic Physic. Electric—Lightning stroke, electric wires. Thermic; Burns, overheat, freezing. Chemise. Inorganic—Saturnism. Organic—Sorghum poisoning, Poisonous plants—Loco, hemlock, larkspur. Poisons secreted by snakes, bees, etc. Parasitic. Bacteria—Glanders, tuberculosis, YVeast—FEpizootic lwnphangitts. Moulds—Pulmonary mycosis. Protozoa—Tick fever. Termes—Trichinosis. EXTENSION. Natural channels—Digestic, urinary, ete. Continuity—Along a muscle, ete. Contiguity—From muscular to connective tissues, ete. Blood—In plasma, leucocytes or red cells, Lymph—In plasma or leucocytes, Nerve fibres—Alongarone. TERMINATION. Fractures, dislocations, sprained tendons. 34 GENERAL CONSIDERATION OF DISEASE. Health has been defined as that condition in which the normal structure and functions of all the component parts of an or- ganized being are maintained. Disease is a functional or structural deviation from the normal. It is that condition in which an organism cannot accustom itself to its environments. Health and disease are, however, only relative terms, because of the difficulty of determining a normal standard. The two conditions necessarily overlap. Diseases may be classffed in many ways, as local and general, infectious and non-infectious, inherited and acquired, ete. INHERITED DISEASES are those transmitted from the parent in spermatozoa or ova and are present at the time of fertilization. Cer- tain characteristics are transmitted from parent to offspring such as genus, breed and individual peculiarities. Thus horses have peculi- arities so fixed and constant that they are transmitted to their off- spring and differentiate them from other specics of the genus Equus. Breeds are differentiated by certain peculiarities; thus Jersey cattle are brown to light fawn in color with a brown muzzle, horns turned in and up, they are small, lean, dish faced, etc., all of which are peculiarities that distinguish them from other breeds of cattle. There are individual peculiarities, some of which are the result of the fusion of parental characteristics; thus the offspring may be of solid color, the result of the fusion of different parental colors, (color blending), or they may be piebald, indicating fail- ure of color blending (mosaic coloring). The extent of intensi- fication of inherited generic, breed or individual peculiarities de- pends upon the prepotency of the parental stock. This pre- potency depends upon the length of time that the type has existed under similar circumstances. The foregoing illustrates what is meant by the term “heredity”, and demonstrates that the breeding of stock is a science. Diseases are rarely inherited, first, because diseased spermato- zoa and ova are probably incapable of fertilization, and second, there is always a tendency to abort when the embryo or foetus is diseased. A predisposition may be inherited, i. e., the progeny of diseased parents may be more susceptible to disease than the progeny of a healthy parentage. Infectious diseases are very rarely inherited. It has been demonstrated that spermatozoa are not phagocytic in action and probably ova have no phago- cytic tendencies ; the latter, however, has not been proven. The quantity of semen and the number of spermatozoa per given volume varies in different animals and in the same animal under 36 VETERINARY PATHOLOGY. different conditions. Loeb estimated that the average human seminal ejaculation contained about 226,000,000 spermatozoa. The average seminal ejaculation of a dog probably contains about the same number of spermatozoa as that of the human. Lewis found that one stallion ejaculated 65 ce. of semen during one service, each emm. of which contained approximately 151,- 750 spermatozoa; another stallion ejaculated 90 cc. of semen dur- ing one service, each cmm. of which contained approximately 225,000 spermatozoa. The quantity and the number of sperma- tozoa per given volume of semen ejaculated during one service of the bull has not been determined, at least the information has not been found in the available literature. However, it is reason- able to suspect that the number of spermatozoa ejaculated dur- ing a single service by the bull is equal to the number ejaculated by a stallion during a single service. It is difficult to collect the entire discharge of semen of a boar, but Lewis obtained 100 cc. from a single service of a boar and by repeated examinations he has determined that the semen from boars contains more spermatozoa per given volume than that from stallions. There would, therefore, be less chance for fertilization with an infected spermatozoon in the horse, ox and hog than in man. Suppose there were 1,000 tubercle bacilli infecting 1,000 spermatozoa that were ejaculated by a bull in one service, then there would be one chance in about 12,000,000 of an infected spermatozoon’ fertilizing an ovum, assuming that one seminal ejaculation of the bull contains approximately the same number of spermatozoa as one seminal ejaculation of a stallion. The chance is so slight that it need not be considered. The offspring of animals affected with some infectious diseases are more susceptible to those dis- eases. For example, calves of tuberculous parentage are more susceptible to tuberculosis than calves of non-tuberculosis animals. Neoplasms or tumors are occasionally inherited or at least there is an inherited predisposition to them. Dr. A. F. Meredith of Lincoln, Kansas, submitted a tumorous growth for examina- tion that was obtained from the left eye of a mule. The dam of the mule, as well as four of her brothers and sisters had a similar defect of the same eye. Cadiot refers to a family of dogs in which there were carcinomata of the mammae for two successive generations. Malformations, though usually of congenital origin, are probably more frequently inherited than is any other type of disease. Thus a cryptorchid stallion was used for breeding purposes in a certain locality in Illinois and about 20% GENERAL CONSIDERATION OF DISEASE. 37, of his male colts were cryptorchids. About 5% of the male progeny of one of Missouri’s most famous boars, Chief Tecum- seh II, were cryptorchids. Liberty Chief and Chief I Know, two boars sired by Chief Tecumseh II, were noted boars and from 3 to 5% of their male get were cryptorchids. Chief Per- fection II, also sired by Chief Tecumseh II, was the sire of Che- rokee Perfection which in turn sired about 3% of ecryptorchids, Thus this structural defect appeared in at least three genera- tions. A female Belgian hare having one ear, produced a large number of young of which more than 50% had only one ear. Epileptic domestic animals and those affected with other nervous disorders are usually destroyed or at least are not bred, hence the statistics of inherited nervous diseases in domestic animals are very meagre, but there is little doubt that such diseases, or at least a predisposition to them, is inherited. La Notte recorded hereditary epilepsy in the progeny of two epi- leptic bulls, the disease becoming evident in the females after they had given birth to their first calves, and in bulls soon after they were put into service. Some other diseases are inherited, thus; periodic ophthalmia has, in many instances, occurred in, and affected practically an entire family of horses. There is a predisposition to spavins, splints and ringbones in certain strains of horses. This is due to inheritance of structural or conformation defects. ACQUIRED DISEASES. The life of mammals is conventionally divided into two periods, the ante-natal or intrauterine, and the post-natal or extrauterine. Acquired diseases are those contracted after fertilization and hence may be ante-natal, (congenital) or post- natal. Ante-natal or Congenital diseases are those contracted — be- tween the time of fertilization and birth. Some infectious diseases are congenital, for instance, marked lesions of tuberculosis were found by the writer in 1900 in a three day old calf, and two authentic reports of similar cases have been received since that date. (These cases were not considered as inherited for the reason heretofore given, and in all three cases lesions of tubercu- losis were found in the uterus and adjacent tissues of the cows.) Infectious diseases are seldom transmitted from the mother to the foetus because of the relation and anatomical structure of the placental membranes. The female is usually either sterile or aborts if the uterus or the accessory parts are diseased, while the male is not likely to be productive if the genital organs are diseased. Exanthematous diseases are frequently congenital. 38 VETERINARY PATILOLOGY. Teratomata and other malformations are diseased conditions and are usually of congenital origin. Post-natal discases are those contracted at any time during the life of the animal after birth, as laminitis, actinomycosis, and spavin. In classifying diseases according to extent, two groups are usually described, viz:—, local and general. 1. A LocAL disease is one that affects a part or organ; as urethral calculi, pulmonary anthracosis, etc. Local diseases proper remain localized although the term is used in a broader sense to desig- nate a circumscribed, local, morbid process that may later be- come generalized. Thus; tubercular infection of a group of lymphatic glands is frequently spoken of as localized tubercu- losis. 2. .\ GENERAL disease, strictly speaking, is one invoking the en- tire animal body, as anemia, but in a more restricted semse it is used to designate the involvement of several parts or organs. Etiology.—Disease has been defined as an inharmonious relation between an individual and its environments. This definition is indicative of the various factors concerned in the production of morbid processes. The causes of disease may be conveniently subdivided into two groups, viz.; predisposing causes and exciting causes. PREDISPOSING CAUSES.—Predisposing causes are those condi- tions or environments whch render animals more — suscept- ible to disease. It has long been recognized that many diseases of domestic animals are due to induced variations of species that result from selection by breeders. New breeds of the various animals are produced so rapidly, that the individuals of the new breeds are more susceptible to disease. Retrogressive changes in anatomical structures predispose to disease. The tarsal joint of the horse is gradually changing from an active to a passive structure; this change results in a tendency to ossification and ankylosis or spavin formation. Pro- gressive changes in various structures are responsible for some diseased conditions, viz., navicular disease in the horse, or dairy breeds having large udders, are more susceptible to mammary diseases. Several breeds of horses are characterized by small heads and especially diminished facial bones, a conformation that predisposes to dental diseases, Inbreeding has been a cause of decreasing the resistance of animals to disease. Age. The age of animals is an important predisposing factor GENERAL CONSIDERATION OF DISEASE. 39 in the causation of disease. The very young animal is struc- turally more delicate than the matured animal. Tissues are more or less permeable to the various bacteria, and until the young acquire an immunity, i. e., establish a resistance, they are more or less influenced by bacterial activity in their tissues. There are some diseases, however, that affect only young animals, as. canine and colt distemper, while Uther diseases occur primarily or only in adults as carcinomata and bursattae. Sev is of consequence in the occurrence of disease. Parturi- tion predisposes females to disease. Males are especially suscept- ible to urethral calculi. Genus may be a characteristic factor in the predisposition to disease. Glanders is a disease of the genus equus, caseous-lymph- adenitis of the genus ovis, canine distemper of the genus canis, rinderpest of the genus bovis. Breed.—There are certain peculiarities of different breeds of animals that are inducive to disease, thus the original Clydesdale horse is not resistant to laminitis; the thoroughbred having a nervous temperament is more susceptible to heart disturbances ; the jersey cow with a diminished breathing capacity is more liable to pulmonary tuberculosis. IVhite or light colored animals are more susceptible to der- matitis and are more affected by flies than those of darker color. In certain locations there are no white hogs because the hogs in those locations feed upon the roots of Lacuanthis — tinctorta, which causes a pink discoloration, (hyperemia), of their bones and causes sloughing of the feet in all except black hogs. Individuals of a resistant strain are sometimes especially sus- ceptible to certain diseases. Location.—The soil of a locality may be deficient in some necessary 1 ingredient or contain some noxious constituent. Some localities may be continually damp and muddy, others dry and dusty, and still others abound in objectionable gases and odors. Any of the above conditions naturally diminish the resistance of animals; thus pica exists in localities in which the soil is prob- ably deficient in some ingredient, scratches and thrush are com- mon where mud abounds: broken and cracked feet in dry dusty regions, and nasal catarrh where irritating odors are common. Climate definitely influences the hairy covering of animals. In Angora, not only goats but also collie dogs and cats have fine fleecy hair. Mules kept in mines constantly for a long time become covered with velvety hair like that of a mole. Season.—Some diseases are more common in certain seasons. aU VETERINARY PATHOLOGY. Thus pneumonia is more prevalent during the seasons of sudden change as early spring and late fall. Occupation.—The city express horse is particularly lable to diseases of the feet, the thoroughbred to rupture of the heart or blood-vessels, the dairy cow to udder diseases, the house dog to indigestion, etc. Food and !ater.—Excessive, insufficient or unwholesome food and water, also irregularity of feeding or watering are fre- quent causes of depressed condition of animals. In Holstein an enzootic anemia destrovs hundreds of suckling pigs annually. The pigs are apparently normal until about two weeks of age. The cause is probably improper food and a predisposition result- ing from excessive stimulation of the reproductive function of the sow. Variegated color of parrots is produced by feeding green parrots fat from siluroid fishes. Colic is essentially a dietary disease. The effects of previous discase frequently leaves an animal in a depleted condition, thus petechial fever is frequently a sequel of pneumonia or “stable fever’? (catarrhal fever). Overwork, lack of exercise, variable temperatures, and other minor causes all have their influence in depressing the animal body. Imitation.—Some animals, colts especially, have a tendency to imitate what other herses do, thus colts allowed to run with cribbing horses occasionally become cribbers. EXCITING CAUSES of disease are those acts or agencies which directly and specifically produce disease as falling, sunlight. chemic substances and infection. Mechanic, physic. chemic and parasitic agencies are the principal exciting causes of disease. Mechanic—Diseases are produced mechanically by break- ing the continuity of involved tissues, by compression, or by changing the relations of anatomical elements. The condition resulting from a break in the continuity of a surface soft tissue is termed a wound, of sub-surface soft tissue, a rupture and of osseous tissue, a Tracture. Compression may cause bruising cr crushing depending upon the mechanical object inducing the in- jury, and the amount of pressure exerted, Luxations or dis- locations are the result of changed relations of bones, tendons and ligaments. Volvuli and intussusceptions are the result of changed relations of the intestine. Hernia is a condition in which there is a changed relation, caused by a break in the continuity of one tissue which permits an adjacent tissue or structure to protrude or sacculate through it. GENERAL CONSIDERATION OF DISEASE. 41 Dogs are more frequently injured by biting than other ani- mals although they may inflict lacerated wounds in other ani- mals especially hogs. Horses more frequently than other ani- mals become injured by pawing, rearing, kicking, falling and colliding with foreign objects. The majority of barbwire wounds are the result of pawing over or through a wire fence. Rearing frequently results in straining the calcaneo-cuboid liga- ment thus producing a curb. Slipping may cause the straining of tendons, thus producing curbs and spavins as well as ten- donitis. Falling may produce strained tendons and is the usual cause of dislocations, rupture, hernia, volvulus and fractures. Runaway horses and mules frequently collide with fences, trees, buildings, and various vehicles, as buggies, wagons, street cars, etc., and thus produce a variety of injuries. Ill-fitting shoes are responsible for contracted feet, strained tendons and ligaments, speedy cuts and bruises by interfering. Illfitting collars produce galled shoulders, sore neck, cerebral venous congestion and sweeney. Illfitting harness produces sweeney, sore neck, sore back, galled sides, rump and tail, an illfitting bridle causes irritation of the mouth, injuries to the eyes, the ears and the throat-latch region, and poll evil. Except- ing the sore mouth, illfitting halters produce the same results as illfitting bridles. Illfitting saddles produce sore backs, sitfasts, injury in the region of girth and bruises resulting in fistulous withers. Attendants may inflict injuries of various types. Several cows in a dairy recently observed, were all lame in the right hind leg. Upon closer inspection the right tarsal joint was found enlarged and sensitive. One man had been milking all the affected cows and finally admitted that he had either kicked or struck each lame cow upon the tarsal joint. Bandages are frequently so tightly wound upon a part that they obstruct circulation thus producing venous congestion, which predisposes to infection. Some cases have been observed in which splints improperly applied to support a part have resulted in venous congestion, oedema and necrosis. Careless individuals will place rubber bands upon dogs’ tails, ears, and feet to see the animals remove them. The dog will sometimes fail to remove the rubber band, which, by pressure, may divide the skin and soft tissues, and finally cause the portion distal to the band to become necrotic and slough. Shooting occasionally causes mechanical injury to animals in pastures, especially during the hunting season. This is more frequently the source of injury during a war, and a knowledge 42 VETERINARY PATHOLOGY, of the various types of bullets and wounds inflicted by same is of considerable importance to army veterinarians. Powdered glass, which is sometimes maliciously incorporated in food for the purpose of destruction of life, may excite gastric and intestinal inflammation. Sand is sometimes consumed in suf- ficient quantities, by animals, grazing upon sandy soil, to mechan- ically interfere with digestive functions, and mechanically injure the gastric and intestinal membrane. Nails, wire, staples, etc., are frequently ingested with food by animals, especially cattle, which objects may abraid and cause injury by producing abra- sions of the mucous membrane or even by puncturing the wall of the digestive tract, thus establishing such inflammatory dis- turbances as peritonitis, pleurisy, pericarditis, ete. Various mechanical contrivances such as operating tables, throwing harness and hobbles, used in subduing fractious ani- mals or confining animals for operative procedure may produce injury. 1. Physic—Temperature variations, not only predispose to disease, but may also become an exciting cause. Excessively high temperature is likely to produce overheat, (insolation, heat prostration). Overheat or heat prostration is frequently ob- served in fat hogs having little or no shelter in the summer time, or in hogs being hauled in wagons or cars, or being driven in herds to market. It is also frequently observed in horses worked on pavements in cities during the summer months, Local application of excessive heat produces burns. The lesions produced in local burns, vary according to the degree of temperature, the length of time applied and the tissue resis- tance. Three grades of lesions, of local burns, determined by the degree of temperature, may be described. First, short expos- ure to a temperature of from 50° to 60° C. produces an hyper- emia or a burn of the first degree; second, exposure to a tem- perature of 60° to S0° C. for a shert time produces inflamma- tien, characterized by a serous exudate that accumulates in the malpighian layers of the epidermis forming vesicles or blisters; third, an exposure to a temperature above 80° C. for a brief period, produces necrosis, the dead tissue becoming dry and hard. Burns involving one-fourth to one-third of the cutaneous surface frequently terminate fatally as a result of excessive heat, hemolysis of the red corpuscles, increased heat dissipation and other disturbed cutaneous functions. Excessively low temperature may diminish the body tem- perature, of warm blooded animals, to the extent that the func- tioning is modified or inhibited sufficiently to result in death. GENERAL CONSIDERATION OF DISEASE, 43 Animals are naturally protected from the effects of low tem- beratures, in dry weather, by their coat of hair, fur, wool or eathers. When their protective coat becomes wet it no longer orevents heat dissipation consequently animals having no shel- ter, as ranch horses, cattle, and sheep, frequently die in great numbers during the early cold spring rains. The local lesions caused by low temperature are practically the same as those resulting from exposure to high temperature. Thus exposure to a mild, low temperature produces hyper- emia ; exposure to freezing temperature produces inflammation accompanied by a serous exudation but the exudate rarely accummulates and forms a vesicle as in burning. Exposure to extreme low temperature produces necrosis, the frozen tissue becoming dry and hard. Animals are most frequently exposed to temperatures suffi- ciently high to produce insolation in the daytime, in the tropi- cal or temperate zones, although overheat is sometimes observed during the night. Exposure to temperatures that produce local burning usually occurs in conflagrations of buildings. Scores of animals die, in the spring, on ranges or large pastures, in the temperate zone, as a result of diminished body temperature in- duced by exposure to cold rains. These animals are usually depleted because of insufficient or non-nutritious food. Their coat of hair or wool becomes saturated with water and thus the body temperature regulation is disturbed. Lesions produced by low temperatures are evident only in regions and seasons, where there is a low atmospheric temperature. Local freezing usually occurs in extremities as the ears, tail and feet. 2. Photic—Exposure to sunlight frequently produces derma- titis, especially in those animals having a thin, light colored skin. White hogs are quite seriously affected by sunburning, in some localities. This peculiarity prohibits the raising of white hogs, in certain districts in Africa and Central America. R. Paine, F. R. C. V. S., of the Department of Agriculture of Cape Colony, in the Journal of Comparative Pathology and Therapeutics, Part 1, Vol. XXI, reported some cases of dermatitis in cattle, that were undoubtedly the result of exposure to sunlight, D. M. Campbell observed about 40 Duroc Jersey pigs affected with derma- titis induced by sunlight. Direct or reflected sunlight is also injurious to the eves of domestic animals. The injurious effects are noticed more especi- ally in animals driven upon macadam thoroughfares or over light colored soil. Electric and gas lights have also been found to be injurious to the eyes of various animals especially 44 VETERINARY PATHOLOGY when the lights are allowed to shine directly into their eyes. Epilepsy has been produced in horses by sudden exposure to intense light. The immediate cause of the effects of exposure to sunlight upon the skin is not known but is thought to be the result of the action of the actinic or chemic rays. The effects of expos- ure to light upon the eyes is excessive stimulation which pro- duces exhaustion thus predisposing to, if not directly exciting disease. 3. Electric—Animals are susceptible to the action of elec- tricity. Horses are especially susceptible to its influences, a direct current of 500 volts, 100 amperes, is sufficient to kill a horse, and an alternating current of 160 volts is destructive to medium sized dogs. Contact with electricity may be the result of lightning, and charged electric wires, or rails. Horses and cattle frequently are struck by lightning while in pastures, and animals used in cities are occasionally accidentally brought in contact with electric currents. Depending upon the amount of electrical current, the results may be a slight singeing of hair, burning, or laceration of tissues in general. Carcasses of animals destroyed by electri- cal currents have also been observed in which no lesions could be found. On examination of carcasses of animals dead of lightning stroke, there is usually more or less singeing of the hair, hyperemia and hemorrhages along the course of the cur- Tene. Chentic—Chemic substances capable of producing disease are very common and may have their origin from the mineral, veg- etable or animal kingdom, and are inorganic or organic. Ili 1 probable that practically all chemic substances may, under cer- tain conditions, be injurious to the tissues of the various animals. Some chemicals are always injurious, others may become in- jurious by chemic change induced by the tissue juices. Those chemicals capable of producing deleterious effects in the animal tissues are poisons. (Poisons are substances which when taken internally or applied bik alter health or destroy life with- out acting mechanically or reproducing themselves. ) According to their modes of action, poisons have been classi- fied as follows: 1. Corresive poisons, (caustics and irritants.) The action of this group varies from the production of a simple hyperemia te necrosis. The most commen agents are mercury, arsenic. sodium and potassium hydroxide and the min- eral acids. 2. Parenchymatous poisons. This group produces tissue Common Name, Ergot Stink Horn Bunch Flower White Hellebore Calif. Hellebore Pokeroot Corn cockle Monkshood Wild Monkshood Wild Monkshood Larkspur (dwarf) Larkspur (purple) Larkspur (Wyoming) Larkspur (tall) Mayapple Wild blackberry Wooly loco Stemless loco Rattlebox Wild or blue pea Wild or blue pea Alsike clover Red Buckeye Horse chestnut Ohio Buckeye Calif. Buckeye Water Hemlock Oregon Water Hemlock Poison Hemlock Broad leafed laurel Narrow leafed laurel Great laurel Black nightshade Spreading night- shade Horse Nettle Jimson weed Tobacco Potato Cocklebur Cocklebur Sneezeweed Death Canas Sorghum Kaffir corn Castor bean ORDER OR FAMILY Hypocracaea Phallaceae Melanthacae Malanthacea Malanthacea Phytolaccaceae Caryophyllacea Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Berberidaceae Prunaceae Leguminosae Leguminosae Leguminosae Leguminosae Leguminosae Leguminosae Aesculaceae Aesculaceae Aesculaceae Aesculaceae Umbilliferae Umbilliferae Umbilliferae Hricaceae Ericaceae Hricaceae Solanaceae Solanaceae Solanaceae Solanaceae Solanaceae Solanaceae Compositae Compositae Compositae Melanthaceae Gramineae Gramineae Euphorbiaceae BOTANICAL NAMES, GENUS Claviceps Uathrus Chrosperma Vevatrum Vevatrum Phytolacca Agrostemma Aconitum Aconitum Aconitum Delphinum Delphinum Delphinum Delphinum Podophyllum Prunus Astragalus SPECIE purpura columnatus muscaetoxicum vivide californicum americana githago napellus 2olumbianum ancinatum tricorne menziesii geyeri glaucum peltatum serotina mollisimus Aragallas (Oxytropis) lamberti Crotalaric Lupinus Lupinus Aesculus Aesculus Aesculus Aesculus Cicuta Cicuta Conium Kalmia Kalmia Rhododendron Solanum Solanum Solanum Datura Nicotiana Solanum Xanthium Xanthium Helenium Zygadenus Andropogon (Hack) Andropogon Ricinus sagittalis leucophyllus. argentus pavia hippocastanum glabra california maculata vagans maculata latifolia angustofolla maximum nigrum nigrum triflorum carolinense stramonium tobacum tuberosum canadense glabratum venenosus Sorghum Sorghum communis POISONOUS PRINCIPLE Ergotine Veratrine Veratrine Phytolaccine Aconitine Aconitine Aconitine Podophyllin (Berberine) Hydrocyanic acid Barium Chloride Barium Chloride Unnamed alkaloid Lupinin Lupinin Aesculin Aesculin Aesculin Aesculin Conine Conine Conine Andromedotoxin Andromedotoxin Andromedotoxin Atropine Atropine Atropine Atropine Nicotine Solanin Hydrocyanie acid Hydrocyanie acid Ricin ANIMALS AFFECTED all Hogs especially cattle especially all all chickens (seed) sheep all chickens especially all all al) cattle and sheep cattle and sheep cattle and sheep cattle and sheep cattle cattle Cattle, Horses and sheep Cattle, horses and sheep Cattle and Horses sheep sheep horses a all cattle and sheep cattle and sheep cattle and sheep all all all all all horses and sheep pigs, cattle and sheep pigs horses, cattle and sheep sheep and cattle cattle cattle all LOCATION OR DISTRIBUTION Universal Southern States Eastern U. S, Eastern and Northern U. 8. California Eastern 2/3 of U. S. Eastern 2/3 of U. S. Universal garden plant N. W. America. North Central U. S., Ga, Pa. Ohio, Ind., Pa., Ky., N. Ga Ga., Ark. . W. U. 8. and 8. Ww. Can. Wyomlng and N. Colo. W. U.S. Fla., Tex. Middle Atlantic States, oh Dak., Kanas., eX. Plains U. S., Mex. and Can. Plains U. S. Mex. and Can. N. Car., Fla., S. Dak., Ark., Western U. valley. Uplands and foothills. Central U. S. uplands and foothills. Central U. S. uplands and foothills. Gulf and middle states, Va. to Fla. N. Eng., N. Y., J. Ohio, Pa., Ala., Mich., Okla., Neb. California. Eastern and Gulf States, N. Mex. Mex. S. especially Mo. river N. W. Uz. S. N. E. U. S. and California. Allegheny district, Fla., La, E. S. Ga., Mich., Hud. Bay, see Found. Allegheny Mts., Universal Nova Scotia, Ont. Ont. N. W. Ter., Kans., Ariz. Central U. S. also Eastern U. 8. Universal Universal Universal Universal Georgia, N. Eng., Fla., Neb., Mex. Universal Western U. S. Plains especially. Plains especially. Universal GENERAL CONSIDERATION OF DISEASE. 45 degeneration, especially parenchymatous and fatty degenera- tions. The most common parenchymatous poisons are the tox- ins, endo-toxins, ptomains, leucomains, phosphorous and silver. 3. Hemic poisons. These act principally upon the red blood corpuscles and may inhibit combination of hemoglobin and oxygen, and cause disintegration of the cells and even produce thrombosis. The principal agents that combine with hemo- globin and thereby produce disintegration of the red cells, are carbon monoxide, sulphuretted hydrogen, hydrocyanic acid, the chlorates, and mercury. 4. Nerve and Cardiac Poisons. These may produce paraly- sis by over-stimulation of nerve centers, or they may produce variation in the rate and force of the heart beat. Narcotics, such as atropine and solanin are types of neurotoxic poisons. Potassium salts depress the rate and increase the force of the heart action. A poisonous drug may act in a variety of ways depending upon the form of the drug, size of dose and method of adminis- tration. The following are the more common inorganic poisons :— arsenic, mercury, sodium, potassium, lead, copper, chlorine, and and the various oxides, salts, acids and bases formed from them. Many organic compounds are responsible for poisoning in animals as phenol, iodoform, picric acid, hydrocyanic acid. In fact most of the medicinal organic compounds are poisonous in large doses. There are many plants that are responsible for extensive losses of live stock in all parts of the United States, Canada and Mexico, and are most extensive in range districts. Colorado and Montana have had losses aggregating $200,000.00 annually, in live stock, from plant poisoning. The following table gives the common and botanical names of plants that most frequently produce poisoning in animals. (See insert No. 1.) These plants are not all poisonous during their entire development. The cocklebur is most poisonous in the earlier stage of development, that is, at the time the cotyledons come through the soil and for two or three days after the plant is up. Lupines are harmful principally while the seeds are maturing. Larkspurs are harmful only until the flowers appear, Dry sea- sons are usually most favorable to the formation of poison- ous principles in plants. Ergot develops most extensively dur- ing the wet seasons. Second growth or stunted kaffir corn and 46 VETERINARY PATILOLOGY. sorghum plants are more likely to be injurious than first growth or well developed plants. Poisonous plants usually have some noxious properties as odor, taste, or appearance that protects them from consump- tion by animals. Poisoning usually occurs in animals that are hungry or are not accustomed to the location, or at least are not familiar with the plants that abound there. Animals in districts where poisonous plants are found are usually familiar with the disagreeable properties of them and let them alone or Fig, 16.—Red Buckeye (Aesculus Pavia), the animals may become accustomed to the injurious principles of the plant, that is, develop a tolerance similar to immunity to infective diseases. : In their vital activities microphytes (bacteria, yeast and moulds) and microzoa (protozoa) produce chemie substances that are extremely poisonous to animals. Thus saphrophytic bacteria produce ptomains in putrefying flesh. Fermented, musty or mouldy hay contains injurious substances that produce indi- gestion in the horse and ox. The specific products of micropara- GENERAL CONSIDERATION OF DISEASE, 47 sites will be discussed under the topic of vital or infective causes of disease. Bees, wasps, scorpions, ants and other animal organisms liberate poisonous chemic substances (zootoxins) which, when introduced into the animal body cause marked disturbances. Poisonous snakes secrete and liberate injurious chemic sub-- Loco (Astragalus Mollissimus). Fig. 17. stances. The pcisonous principle, zootoxin or venom is pro- duced by glandular tissue, and is lberated through canals or grooves in their fangs. The exact chemic composition of venom has not been determined but is not the same in the different venomous snakes. Noguchi has classified the principle action of venom as follows :— 48 VETERINARY PATHOLOGY. 1. Instantaneous production of thrombi. Crotalus (rattle- snake). (ra 2. Neurotoxic action. (Cobra.) 3. Produce capillary ruptures and hemorrhage. Crotalus ttlesnake). +, Produce hemolysis. Crotalus (rattlesnake). 5. Produce general cytolysis. Crotalus (rattlesnake). and viper berus (adder). The following is the toxicity estimate of venom per kilo- gram bedy weight :— Cobra venom .00009 gram lethal dose for horse intravenously. Cobra venom .0005 gram lethal dose for dog subcutanously. Rattlesnake .005 gram lethal dose for rabbit subcutanously. Viper .0001 gram lethal dose for rabbit intravenously. Retrograde metamorphosis in the tissues of the animal body frequently results in the production of leucomains which when absorbed are extremely poisonous and cause marked disturb- ances. Over action of muscular tissue may cause the produc- tion of leucomains, thus horses that are overworked, although the are ir food and water are first-class and their digestion is good, occasionally affected with a severe diarrhoea caused by the action of leucomains. Parasitic or Infectious. During the last quarter of a century pat hology has received an impulse by the knowledge of micropar- asites acquired during this time. Although parasitism has been known since the dawn of the 19th century the importance of microparasites has been recognized only siace bacteriology be- came a science. lon Parasitism is an evolutionary condition. It is the result of a ¢ continued struggle, and the survival of the fittest, during which there is a necessary adaptation to constantly changing en- vironmental conditions. Parasitic causes of disease include rep- resentatives of both the plant and animal kingdom. Parasitic plants (Phytoparasites) are practically all microscopic in size and are termed microphytes. Pathogenic plants are all fungi and the following scheme gives their position in the plant king- dom: VEGETABLE PARASITES. KINGDOM BRANCH CLASS ORDER FAMILY GENUS SPECIES 1. Plant Thallophyta Hyphomycetes ................ Mucidineae Oospora Porrigines (Achorion schoenleini) 2. Plant Thallophyta Hyph»mycetes Plecascineae Aspergillaceae Aspergillus Fumigatus 8. Plant Thallophyta Hyphomycetes Plecascineae Arpergillaceae Aspergillus Niger 4. Plant Thallophyta Ascomycetes Protoascineae Saccharomycetaceae Saccharomyces Farciminosus 5. Plant Thallophyta Schizomycetes ..,...cceceree ceeereeee ere Actinomyces Bovis 6. Plant Thallophyta Schizomycetes ,,....... de aie cistatgi Thesis eee eae Bacterium Tuberculosis, etc GENERAL CONSIDERATION OF DISEASE. 49 Hyphomycetes (Moulds). Hyphomycetes or moulds are non-chlorophyllic plants. Struc- turally they are composed of mycelial threads from which up- right reproductive organs may be formed. ‘They are usually multicellular and reproduce by spores. They require preformed foods and thrive best in the absence of light. Oospora porrigines (chorion Schoenleini) is the organism that causes favus. These organisms have mycelia with hyphae, the latter may be branched and terminate in bulbous ends. The mycelium is later converted into oval spore-like bodies. Favus is occasionally observed in dogs and cats, more rarely in horses and fowls. The disease is characterized by dry scales which are brown, yellow or even white upon the surface and vary from white to sulphur yellow in their deeper layers. The areas involved are usually not more than 14 or 34 inch in diameter, and are usually devoid of hair. The lesion may occur on the head, especially on the forehead, cheeks or ears, and on the abdomen, or outer surface of the hind legs. Sporotrichium Audouini (Trichophyton Tonsurans) is the fungus that causes ring-worm (tinea tonsurans). This fungus is Fig. 18.—Trichophyton 'Tonsurans. showing mycelium and spore like bodics 50 VETERINARY PATILOLOGY. found in the lesion and is probably strictly parasitic. Structurally it is composed of a simple or branched mycelium which may become broken up as a thread of ovoid spores. The spores may also appear in groups in the hair follicles. The disease becomes evident because of the presence of small circular hairless patches which are covered by grayish crusts or scales. As the disease progresses the central portion of the lesion becomes normal and the peripheral tissue becomes involved. This condition has been observed in the horse and ox: other domestic animals rarely become affected. Aspergillus Fumigatus is responsible for an occasional out- break of pulmonary mycosis (Pneumo-mycosis Aspergillosis ) in birds. This fungus is of common occurrence in nature. Structurally the fungus consists of a segmented mycelium Fig. 19.—Aspergillus Fumigatus. which may branch dichotomously and from which upright stems termed hyphae may originate. These hyphae may be segmented and terminate in club-like heads. A tuft of hair- like projections (sterigmata) develops from the hypha head and on the distal end of each hair there is a spore bearing organ (comidium). The entire hypha head with its spore bearing organs is included in a capsule the rupture of which is nec- essary for the distribution of the spores. The spores of Asper- gillus are present in large numbers in hay, straw, barn-vard GENERAL CONSIDERATION OF DISEASE. 51 manure, ete., and they maintain their vitality in the dormant state for a considerable length of time. The source of infection is contaminated food, water or air. The principal lesions are located in the trachea, bronchi, lung and air cells of bones. The disease is characterized by a fibrinopurulent inflammation of the mucous membranes of the trachea and bronchi and abscess formation in the lung. Aspergillus Niger is probably responsible for the cause of some cases of ear canker in dogs. Saccharomyces. (Yeast). Saccharomyces are the budding fungi. The classification of this group, the yeast plants, is as yet incomplete, their general biologic characteristics not being well known. ANN ee SS. (et te, Fi >—Taenia Echinococcus. Niles & Neumticn a. Adult fant worm After Neuman, b. Part of hog’s liver showing cystic form, soft and contractile, no articulated uppendages, no orguns of special HELMINTHES body excretory organs arranged in pairs. INSERT IV. Invertebrata, sense, CLASS PLATYHELMINTHES, Flat worms, nearly hermaphodites, NEMATHELMINTHES, Round worms, mented, nonseg- sexes separate. ORDER CESTODA, Ribbon shaped, segment- have no fixation apparatus have no digestion apparatus on head. Adult lives in in- testines. TREMATODA, F:at worms, nonsegment- ed, have digestive canal, no anus, have one or two suckers on ventral surface. ACANTHOCEPHALA, Slender worms, complete digestive canal, are found in all tissues of domestic animals except bone. WNEMATODA, Slender worms, complete digestive canal, are found in all tissues of domestic animals except bone. FAMILY TAENIIDAE, Head always has_ four suckers between which is found a depression or a proboscis, Segments usu- ally have their gentlal op- enings on margin. BOTHRIOCEPHALIDAE, Found mostly in fishes. DISTOMIDAE, All have two suckers, an anterior and ventral. ECHINORYNCHIDAE, Found in digestive canal of vertebrates. ASCARIDAE, Large firm body, resemble earth worms, mouth is surrounded by three lips. Usually found in smal] in- testine, OXYURIDAE, Cylindroid body, tail pointed, mouth nude, stomach large. STRONGYLIDAE, Body cylindroid, mouth either nude, armed = or papillated, oseophagus large. TRICHOTRACHELIDAE, Body slender in anterior portion, eniarged poster- iorly for containing intes- tine, mouth nude, anus terminal, all live in intes- tine. FILARIDAE, Long thread llke_ body, mouth or triangular ,oeso- phagus small. GNATHOSTOMIDAE, Head distinct, oviparous. GE) Taer Tae Taer Taer Taer ‘Vaer Taer Taer Taen (Cys Taen Taen Tacni Both Disto Disto Disto Amp! Parag Eehii Ascar Ascar Ascar Ascar Ascar Ascar Oxyur Oxyur Stron Strong Strong Strong Strong Strong Strong Strong Strong Strong Strong Sclera Sclera Sclera Tricho Triche Tricho Tricht Filarit Filarlt Filarit Spiroph Spirop Spirop Spirop, Spirom, Gnath SPECIES HOST aginatta Man yst; Cysticercus cellulosae, of pig.) solium , Man yst; Cysticercus bovis, of ox.) erfoliata Horse amiliana Horse licata Horse enticulata Ox xpansa briata paces te arginata Dog oenurus chinococcus ucumerina st; 'yst; (2) ephalus latus hepaticum lanceolatum Americanum oma cervi imus Westermanii hynchus gigas marginata mystax eurvula mastigodes lus Arnfeldi us micrurus lus pulmonaris lus filaria lus rufescens lus paradoxus lus Osteragi lus contortus lus filicollis lus gigas lus vasorum oma equinum oma tetracanthum oma hypostomum us trachealis jurus dentatus ia trigonocephala ia cernua ia radiatus phalus affinis sphalus crenatus sphalus depressiusculus spiralis papillosa cervina Immitis ra megastoma ra microstoma ra reticulata ra scutata ra sanguinolenta tomum cheiracanthus sticercus tenuicollis of rumin ants.) Dog, wolf and fox st: Coenurus cerebralis in spinal co1d and brain of sheep.) Dog and wolf yst; Echinococcus polymorphous, of herbivora and omnivora.) Dog (1) Cryptocystis trichodectis of Trichodectes latus.) Cryptocystis pulecides of Pulex serraticeps.) Man, dog, cat Herbivora and omnivora Sheep, ox, goat, pig, ass, dog Sheep and ox Ruminants Man, dog, pig and cat Pig Solipeds Ox Sheep Pig Dog Cat Horse Horse Solipeds Bovines Calf Sheep, Sheen, Pig Ox Sheep, Sheep Horse, Dog Horse, ox, dog and Solipeds Sheep and goat Birds and chickens Pig Dog and _ fox Sheep and goat Bovines goat, camel, deer goat and deer goat and goat ox, dog and man man Ox, sheep and goat Pig Dog Pig Horse Ox and deer Dog Horse Horse Horse and goat Ox, sheep Dog Pig, dog and cat PART INFESTED Intestine Intestine Intestine Intestine Intestine Intestine Intestine Duodenum and gall duct Intestine Small intestine Small intestine Small intestine Intestine Gall ducts Gall ducts Liver Rumen Lungs Small intestine Small Intestine Intestine Intestine Intestine Intestine Intestine bowel bowel Posterior Posterior Bronchi Bronchi Bronchi Bronchi Bronchi Bronchi Abomasum Abomasum and duodenum Small intestine and abomasum Kidneys and arinary organs Heart Intestine Large intestine Large intestine Trachea Region of kidney and liver Small intestine Small intestine Small intestine and lungs and lungs and lungs Caecum Large Caecum Muscles intestine Peritoneal and plural cavities Peritoneum Right heart and pulmonary arter- ies Right stomach Stomach Flexor tendons asd cervical Hga- ments Oesophageal wall Tumors of stomach, aorta gullet and Gastric mucosa GENERAL CONSIDERATION OF DISEASE. Fig. 37.—Strougylus Micrurus, after Raillict. a. Male and female. b. Caudal extremity of male. OS VETERINARY PATHOLOGY. a Part of Fig. 38. B A Fig. 38.--Strongylus Paradoxus, after Rail liet. a. Adult male and female. b Caudal extremity of female. ce. Caudal extremity of male. J ee \ f TNT JS N. Race f IH ) Dy Had | Ht HA 1 } if i ih i Hi Fig. 39a. and b. Fig. 39¢. a Adult male. b. Adult female. e. Cephalic extremity enlarged. Fig. 39. Filaria Panillosa, after Neuman. BRANCH INSERT V. ARTHROPODA arranged tn pairs. jointed appendages Invertebrates with CLASS INSECTA (HEXAPODA), Air breathers, when adult have three pairs of legs, and distinct head, thorax and abdomen. ARACHNIDA Air breathers with caphal- othorax and abdomen, have when adult four pairs of legs. Those here included are oviparous. ORDER DIPTERA Have two wings, two hal- teres, sucking mouth parts, and complete metamor- phosis, includes flies and mosquitoes, HEMIPTERA Wings often absent, when present one pair thick and one pair thin., Sucking mouth parts, incomplete metamorphosis, and include the blood sucking lice. MALLOPHAGA Wingles lice with sucking mouth parts, and incom- plete metamorphosis, SIPHONAPTERA Wingless fleas with suck- ing mouth parts, and com- plete metamorphosis. ACARINA Usually short thick, non- articulated bodies, possess camerostoma, larva usual- ly hexapodal, sexes sepa- rate. LINGUATULIDA. Internal parasite, elongat- ed, vermiform, annulated EAMILY MUSCIDAE Have soft probosis adapt- ed for suction, stylet of an- tennae plumose to the end. TABANIDAE Broad and slightly flat- tened body, large head, muscular wings, larva car nivarous, are oviparous. STOMOXIDAE Closely resembles the mus- cidae. SIMULIIDAE Thick body, bulging tho- rax, .egs strong. HIPPOBOSCIDAE Flat body, head notched into thorax, legs. strong, pupiparous, OESTRIADAEB Body usualiy hairy, large wings, proboscis very small, oviparous. CULICIDAE Have song slendor abdo- men, wings fringed with hairs, antennae plumose in males, oviparous. : PEDICULIDAE Blood suckers, proboscis formed of upper and lower lips and armed with small spines, contains protrusile tube or sucker, oviparous. RISCINIDAE Not blood suckers, have long masticatory apparatus with which they eat epi- dermic wyroductions, ovi- parous, PULCIDAE Very agile, brown oval bodies, compressed latter- ly, biting mouth parts in larval stage. IXODIDAE Large globular blood-suck- ers, oviparous, have undi- vided hypostome. GAMASIDAB Rostrum arranged for pricking or sucking, have no eyes. TROMBIDIIDAE Soft, hairy, bright colored, rostrom a conical sucker. SARCOPTIDAE Smalest of the acarina, body soft, white or red- dish, eyes absent, ovipar- ous or ovoviviparous. DEMODECIDAE Very small, vermiform, hairless, cephalothorax and abdomen distinct, legs short, oviparous. LINGUATULIDAB Body segmented, com- pressed dorso-ventrally, crenelated. Pe eer 7 Bo Bo A Del Orr Ixo ATs Der Tro Lep Sar Sar Sart Sart Sart Psso1 Pso! Dem Der Dem Ling SPECIES domestica vomitoria haga carnaria ys calcitrans obia serrata omyia macellaria s atratus s lineola a morsitans m pecuarum hagus ovinus osca equina philus equi philus hemorrhoidalis erma lineata Ss ovis equinus pipiens oles punctipennis ia fasciata opinus macrocephalus opinus eurystermnus opinus vituli opinus piliferus opinus irritans opinus stenopsis ectes pilosus ectes scalaris ectes spaerocephalus destes latus irritans serraticeps avium lus annulatus lus Australis mma Americanum entor electus doros Megnini ricinus miniatus yssus gallinae dium holosericeum irritans es scabei-var, equi. es scabei var. ovis. es scabei var, suis. es scabei var. canis. es mutans es communis var. equi s communis var. bovis. es communis var. ovis. ep scabei var. equi. es scabei varfl bovis. es scabei var. ovis. es aureicularis var. felis x follicurlorum var. equi. x folliculorum var. bovis. x folliculorum var. cani. ula taenloides es auricularum var. cani. HOST Not generally parasitic Animals Animals Animals Animals Animals Animals Animals Animals" Animals Sheep Horse Horse Horse Ox Horse Sheep Animals Animals Animals Horse Ox Ox Dog Pig Goat Horse Ox Sheep Dog Man Fowls Ox Ox Ox Sporting dogs Horse, ox, sheep and dog Sporting dogs Fowls Fowls Animals Man and animals Horse Sheep Pig Dog Fowls Horse Ox Sheep Horse Horse Ox Dog Dog PART INFESTED Wounds Wounds Skin Skin Wounds Skin Skin Skin Skin Skin Skin around perinaeum M, M. of stomach M. M. of stomach and _ intestine Dorsal cutis and subcutis Sinuses of head Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Nasal cavities GENERAL CONSIDERATION OF DISEASE. 69 Fig. 40.—Oxyuris Curvula, after Niles. a. Adult worm 2. Caudal. b. Cephalic extremity, sicollis inhabits the liver of the rat during its cystic stage and the intestine of the cat during the adult stage. Helminthes produce injury to their host by consuming food, by sucking blood and by liberating injurious chemic substances. Arthropoda. This branch includes many parasitic representatives, as flies and mosquitoes (diptera), fleas (siphonaptera) lice (hemip- tera), itch mites and ticks (acarina). The entire order, siphon- aptera and hemiptera, most of the order acarina, and many rep- resentatives of the order diptera are parasitic. Of the parasitic arthropoda some are temporary and some are permanent para- sites, and with one or two exceptions they are all external para- sites. The structural peculiarities that differentiate arthropoda from 70 VETERINARY PATILOLOGY, Fig. 42.—Selerostoma Hypostomum, after Railllet. a Cephalic extremity enlarged. b. Adult female. 2. Adult male. Pic. 41—Syngamus Trachcalis, after Raillict. a Adult worm natural size. b. Male attached to female enlarged. Fig. 48.—Trichocephalus Depressiusculugs Ci Female enlarged. of a Dog, after Raillict, the other branches of the animal kingdom are their jointed ap- pendages, segmented body, and bilateral symmetry. The parasitic arthropoda obtain their food from their hosts. Some of them consume epidermal scales and hair, e. ¢. the GENERAL CONSIDERATION OF DISEASE, 7 Fiz 44.— Melonphagus Ovinus, after Niles a. Dorsal view of adult, d. Terminal segment of leg b Ventral view of adult e. Shell of pupa e. Mouth parts enlarged. f. Pupa. horse louse (Trichodectes Pilosus) and feathers, e. g., the chicken louse (Menopon Pallidum) others abstract blood, e. ¢., the hog louse (Hematopinus Suis), Itch mite (Sarcoptes scaber variety canis), and still others may consume tissue cells other than blood cells as epithelium. Reproduction of arthropoda is about the same as it is in helminthes. Disease resulting from infestation of arthropoda is due primarily to irritation induced mechanically or by chemic pro- ducts of the parasites, secondarily to loss of blood. VETFRINARY PATHOTOGY. Fig. 45—fPart I. Gastrephilus Eoui, after Niles. a. Adult female. b. Adult female. © Young larvae. d Full grown larvae. oe. Eggs cemented to hair. r Egg shell showing lifting of operculum s. Adult male, h. Terminal segments of male. i Terminal segments of female. Fig. 45.—Part II. Oestrus Ovis. a. Adult female. ec. Dorsal view of larva. b. Adult male, after Rily. d. Ventral view of larva, after Rily and Niles. GENERAL CONSIDERATION OF DISEASE. 73 ‘For qe PON NTA ma tT be) aMdiyaiaie ih es Ni A ON Fig 47.—Culex Pungens, after Howard. a. Female b. Male. c. Larva. 74+ VETERINARY PATIICLOGY. Fig. 48.—Asearis Mystax, after Niles. a. Adult male. a. Cephalic extremity. b. Adult temale. d. Caudal. Extension of Disease—By extension of disease is meant the invasion and affection of adjacent structures and even remote tissues of the body. Some diseases are necessarily local, 1. e., the cause is not capable of being transferred to adjacent or re- mote structures, e. g., ocular filariosis. Other diseases are in their earlier stages local, but later the cause may be transferred to some other part and produce secondary diseased foci or Fig. 49.—Distoma Hepaticum. . Intestines. b. Oral sucker. ec. Ventral sucker. d. Uterus metastases, e. g., tuberculosis. The extension of disease may be produced as follows: : First, by the cause of tha disease passing along the natural channels and establishing secondary diseased foci, thus, Bray reports that calves become affected with necrotic gastritis and GENERAL CONSIDERATION OF DISEASE, Ny we enteritis when allowed to swallow the necrotic tissue during an attack of necrotic stomatitis. Second, by the spread of the cause into adjacent tissucs, e. Lt *8: Ss: Extension in like tissue, as in muscular tissue, is continuity as psorospermosis, while extension from one tissue to another of a different type, as from muscular to connective tissues, is con- tiguity as in actinomycosis. Third, by the lymph and lymphatic nodes, e. ¢. tuberculosis. S Fig. 50.—Echinorhynchus Gigas, after Niles, a Cephalic extremity showing hooks i b. Worm with portion of mucans membrane of intestine attached, Fourth, by the blood stream in which case the mestastases will be in the lungs, liver or kidney.—e. g. anthrax. Fifth,by passing along the nerve fibers as in rabies. Termination of Disease.—Termination is the ending or out- come of the condition or existing disease. Disease terminates as follows :— Recovery.—Disease terminates in recovery when the body tissues are effectually repaired and all structures have assumed their normal function. Diseases resulting from irritating or non-nutritious foods are corrected by expulsion or neutraliza- tion of the causative agent either by vomition, purgation or chemical union and by repair of the injured tissues, after which normal functioning continues. Tissue afflicted with mechanical 76 VETERINARY PATHOLOGY. injuries as wounds, recover when the destroyed portions have been replaced and the normal function has been resumed. Dis- locations terminate in recovery when the dislocations have been reduced and the parts assume their normal function. A horse recovers from pneumonia when the inflammatory exudate has been removed from the alveolar spaces and all injured Pig. 51.—Trichina Spiralis, after Colin big. 52.—Trichoedectes Latus, after Niles. a. Dorsal view. b. Egg cemented to hair. c. Ventral view. GENERAL CONSIDERATION OF DISEASE. 77 tissues have been repaired and the normal functioning has been re-established. In general, recovery is the result of the activi- ties of the protective and reparative processes of the various tissues of the animal body. Partial recovery.--lf the normal funtioning is not assumed after a disease has run its course, recovery is said to be incom- plete or partial. Partial recovery is observed in old animals or in those that have been depleted because of complications or previous disease. Some diseases are essentially destructive and their influence in the tissue results in incomplete repair, as in tuberculosis, glanders, dourine, bovine contagious pleuro-pneu- monia, etc. Injuries and acute intammation of the parieties of hollow organs frequently terminate in the formation of cicatrical tissue thus contracting the lumen of these organs. This 1s com- mon in injuries of the oesophagus, intestine, trachea, and ure- thra. Adhesions succeeding pericarditis, pleuritis, and periton- itis are examples of partial recovery. Peath—Disease may terminate in the cessation of all func- tions, i. e. death. The more important specific modes of death are as follows ale Syncope, or heart lage: a result of paralysis of cardiac nerves or muscles, rupture of heart walls or complete obstruc- tion to emerging vessels of the heart. Nerve paralysis may be the result of poisonous products derived from infectious agen- cies, or chemic poisons derived from katabolism, or hemorrhagic extravasates. 2. Apnoea, or respiratory failure. This may be the result of paralysis of respiratory nerves or muscles, spasms of res] piratory ae rupture of diaphragm, or occlusion of the respiratory tubes. a 3. Apoplexy, or hemorrhage into the brain tissue. This is erenee the specific cause of death in apoplectiform anthrax. 4. Hemorrhage, especially rapid loss of large quantities of blood. Anv of the above may act independently in producing death, but are probably more frequently complicated one with another. CHAPTER III. IMMUNITY. DEFINITION. (IMPORTANCE. VARIETIES. Inherited, (Natural). Definition. Examples. Cause. Cell Action, (Metchniko# & Sternberg). Chemic Substance, (Ehrlich & Buchner). ACQUIRED, (Artificial). Definition. Examples. Varieties. Active. Definition. larieties, (Toxic), (Bacterial). Etiology. Recovery from attack of disease. Inoculation with virus. Inoculation with vaccine, Tnoculation with bacterin. tnoculation with toxin, Inoculation simultancously with virus and antibody. Passive. Definition, Etiology. Tnoculation with antibody. THEORIKS. Exhaustion. Retention. Phagocytosis. Humoral. Ehrlich’s Lateral Chain Theory. Immunity literally means proof against disease, 1. e., it is the name of the condition that enables an animal to resist the action of pathogenic micre-organisms, or to be unaffected by their products. Immunity is only a relative term, the condition is not absolute and permanent neither is it constant and con- tinuous. Whenever an animal is unable to adjust itself to its environments it becomes susceptible to the effects of the causa- tive agents of diseases, i. €., its immunity, at least acquired immunity, is suspended. The term immunity is ordinarily used in reference to infec- tive diseases, i. e. those diseases resulting from the invasion of microparasites; although it may be used in designating the resistance to the action of zootoxin, such as snake venom, and possibly also of the poisonous substances ejected by centipedes 78 IMMUNITY. 79 and scorpions, as well as the phytotoxins, such as ricin, abrin, crotin, and robin. Immunity, more than any other problem, directly concerns the medical profession and indirectly the international commer- Fig. 53.—Hematopinus phalanges ovis, after Niles. a Adult. b. Egg cemented to hair. cial welfare. It was a laboratory fad of the pathologists until they demonstrated to the practitioners that it was feasible to produce immunity in man and animals. Veterinarians have now Fig. 54.—Pulex Serraticeps, after Tuszcr 80 VETERINARY PATILOLOGY. almost universally accepted the proposition and have at their command the means by which they can immunize animals against the ravages of some of the fatal infective diseases to which they are susceptible. The increased confidence of the people is in turn enabling scientists to investigate new phases of the subject. Although immunization has been known and made use of more or less for centuries as vaccination against Fig. 55.—Margarapus Annulatus, female. Fig. 56.—Margarapus Annulatus, male. Vig. 57.—Margarapus Annulatus, Fig. 58.—Margarapus Annulatus, Larva. female laying esis3. smallpox by the Chinese before the Christian era, yet the essen- tial physiclegic, chemic or pathologic basis for immunity is still unknown. Immunity may be natural (inherited) or artificial (acquired). Natural immunity is an inherited property possessed by or- ganisms (animals). The horse has a natural immunity to hog cholera, the ox to glanders and the hog to tick fever. The concise and exact cause of natural immunity is unknown. It is probably the result of cellular activity in the immune animal, an activity the nature of which is not understood. Some inves- tigators, Metchnikoff in particular, attribute natural immunity to phagocytosis (cellular hypothesis), others maintain that insus- IMMUNITY. 81 ceptibility to disease is a result of the antagonistic action of the body fluids (humoral hypothesis). Ehrlich’s lateral chain the- Ory assumes that the cells of immune animals are not capable of combining with the toxins of bacteria, i. e., they have no receptor molecules and hence those animals are not receptive, they are immune. Whether we accept the cellular hy pothesis, the humoral hypothesis, or Ehrlich’s lateral chain theory, the fact remains that natural immunity is a characteristic or prop- erty of parental origin that is transmitted to the offspring and is present at the time of birth. Natural immunity may be the result of an acquired toler- ance due to natural selection and heredity. There is a marked variation in susceptibility and resistance in individuals of a given species. A continuous or repeated exposure of susceptible ani- mals to a given pathogenic microparasite will result either in i VAY } wh “i a vas Fig. 59.—Ixodes ricinus, female, after (B. A. I.) destruction of those animals or the production of an immunity, i. e., those individuals least resistant will survive and their resistance will become more and more fixed and will finally be transmitted to the offspring and hence be a natural immunity. Thus all native Cubans are practically immune to vellow fever because at the time yellow fever was first introduced into Cuba the least resistant individuals died of the malady, the most resistant individuals survived and lived in the presence of the diseases almost continually after yellow fever was introduced into Cuba (It was not eliminated until after the Spanish-Amer- ican war). Consequently the Cubans for several generations developed in the midst of yellow fever and only the resistant individuals survived. This resistance finally became so firm 82 VETERINARY PATIOLOGY. that it was transmitted to their offspring and was then a nat- ural immunity. The resistance possessed by dogs to most diseases 1s ex- plained in a similar way to the Cubans’ resistance to yellow fever. Thus the dog has descended from the jackal and the wolf, two types of animals that have lived largely upon the carcasses of animals dead of various diseases. As the animals fed on carcasses they fought, thus inoculating each other, so in the beginning the least resistant individuals died, the more resis- Fig. 60.—The scab mite of sheep, Psoroptes Communis Ovis, magnified 150 diameters. tant animals survived. Thus the constant fighting and inocu- lating has established in them a firm resistance that is trans- mitted to their progeny as a natural immunity. This immunity has become so fixed that it does not vary even in the domestic dog. The above is a plausible explanation of race or species immunity. The exact origin of individual immunity is considered by some to be an acquired tolerance, 1. €., an acquired immunity, and by others, as simply an individual resistance not developed by having the disease to which the given individual is immune. Acquired immunity is an artficially produced condition by virtue of which the animal is capable of resisting disease, and IMMUNITY. 83 is produced in an animal either in utero or after birth, and may be active, or passive, bacterial or toxic. Active acquired immunity is, no doubt, the result of cellu- lar action and may be produced as follows :— 1. By an animal becoming infected and recovering from an attack of the disease, e. g. blackleg. 2. By inoculation of a susceptible animal with a small quantity of the virulent causative microparasites, thus produc- ing the disease in a mild form. This is practiced in immunizing cattle against tick fever. Fig. 61.—Demodex Folliculorum, Fig. 61a.—Demodex Folliculorum, vaiiety Canis. varicty Canis. Field showing various stages of Adult Male, magnified 400 times development showing wide head, with ros- a. Ova. trum, short legs (3 articles cach) b. Pupa. 2 claws and clongated body e. Adult. d. A piece of Scab. 3. By inoculating a susceptible animal with an attenuated virus, (vaccine.) Horses, mules, cattle, and sheep are immun- ized to anthrax by a vaccine. 4. By repeated inoculations of a susceptible animal with small quantities of a toxin of a specific pathogenic microparasite. tetanus toxin or other active poison as snake venom. This method is used only in the production of antitoxins or in immun- izing animals against zootoxins and phytotoxins. 84+ VETERINARY PATHOLOGY. 5. By simultaneous inoculation with a virus and an antitoxin (antibodies, bactericidal substances, etc.) In the Philippine Islands this method is employed in immunizing cattle against rinderpest, and it is also being successfully used in the immun- ization of hogs, against cholera. Toxic immunity is the resistance to poisonous substances as toxins of bacterial origin, zootoxins and phytotoxins. It 1 common to hear sheep herders speak of dogs that are immune to the venom of rattlesnakes. The dogs are bitten frequently while doing duty on the range and although the reaction from the first inoculation is intense and may even kill, each succeed- ing inoculation produces less reaction until finally the dogs may be bitten or the venom inoculated with impunity. Immunity to intoxication diseases such as tetanus are of this type. The ab- sence of action of various therapeutic agents that have been given repeatedly may be explained on the principles similar to those invelved in the production of immunity in dogs to snake venom. Toxic immunity is the result of the presence in the body fluids of an antibody (Antitoxin.) wn Bacterial immunity is the resistance an infected animal manifests to the bacterial invader. It is the result of bacteri- olytic substances in the body fluids. Pfeiffer demonstrated that bacteria are destroyed when introduced into an immune animal. Ile introduced the spirilla of Asiatic cholera into the peritoneal cavity of guinea prgs and noted that the bacteria were soon rendered immobile, became swollen and granular and were fin- ally disintegrated. This phenomena has been designated Pfeif- fer’s reaction. Passive acquired immunity consists essentially of the presence in the tissues or body fluids of substances inimical to micro- parasitic activity, or substances capable of union with micro- parasitic products, (toxins) thus rendering them inert. This type of immunity is of short duraticn. It is usually produced by the inoculation of susceptible animals with antitoxin. Injured animals inoculated with tetanus antitoxin at the time of injury are thus immunized to tetanus for a brief period. Acquired immunity, like natural immunity, is variable and inconstant. The production of active acquired immunity entails more risk than the production of passive acquired immunity. The causative agents or their toxic products are used in obtain- ing an active immunity and thus disease may be produced and the animal life sacrificed while the anti-toxin is used in the production of a passive immunity, without danger of the pro- duction of disease although transient disturbances may result IMMUNITY. 85 from hemolysins, contained in the blood in which there is anti- toxin. Theories of acquired immunity—Many theories have been ot ft Cha ‘a Fig. 62.—Bacterial Immunity. ce. Amboceptor. Compliment Legend— a. Cell body. oO. b. Cell receptor. advanced in explanation of acquired immunity. The chief of which are as follows :— 86 VETERIN*RY PATHOLOGY. 1. The Exhaustion Theory—This theory was championed by Pasteur, who proposed it about 1880. It is based upon the supposition that there are certain substances in the animal body that are food for micro-parasites and that these substances are not regenerated. Hence when they have been consumed the micro-parasites cease to develop and the animal becomes im- mune. ‘This theory is not tenable because immunity can be produced by bacterial products and by dead bacteria neither of Fig. 63.—Hematoba Serrata, after Riley and Howard. a ose c, Pupa. b Larva d Adult fly. which consume substances from the tissues of an animal immun- ized. 2. The Retention Theory.—In the study of bacteriology it has been found that bacteria, like most other organisms, can not develop in the presence of a large quantity of their own excrements. This theory presupposes that bacterial products remain in a body after it has been infected and that these products prevent the future development of like bacteria. This theory does not explain the production of an immunity with toxines and is not supported by any scientists at the present time. The theory was proposed by Chauveau. 3. The Phagocytosis Theory.—This theory was proposed independently by Sternberg and Metchnikoff about 1881. The theory was the outgrowth of the experimental study of the action of leucocytes upon bacteria and yeast, in which it was IMMUNITY. 87 found that certain leucocytes are active in the destruction of various bacteria, yeast and tissue debris. These investigators designated those leucocytes active in the destruction of bacteria, phagocytes. Phagocytosis is a state or condition characterized by the development of phagocytes and the display of their special function. The supporters of this theory hold that the cells, which are active in the production of leucocytes transmit the property of phagocytosis to their progeny and thus immun- ity is perpetuated after it has been acquired. That phagocytes do incorporate bacteria and other foreign substances is not denied but it has not been demonstrated whether phaogocytosis is the cause or the result of immunity. This theory does not explain immunity from such diseases as tick fever. The microzoon of tick fever inhabits and usually flestroys the red corpuscles. The leucocytes are probably not atfected by them. In fact, the presence of the eeeee ee bigem- inum in leucocytes has not been noted. More recently \Wright and Douglas have demonstrated that certain substances in the blood serum are necessary to prepare bacteria for phagocytic action. These substances have been designated opsonins.” Opsouins are chemic substances in blood serum that render bacteria subject to the action of phagocytes. Opsonins resem- ble the amboceptors of Ehrlich in action, but they are not iden- tical with them. The action of opsonins is evidenced in pneu- monia, pyogenic infections, tuberculosis and probably in other diseased conditions. The opsonic index indicates the relative power of resistance due to phagocytic action in an animal body. 4. Humoral theory.—After the phagocytic theory had ben found insufhicie: at, immunity was explained from a chemic view point. ‘he supporters of this theory, among whom Buchner was active, demonstrated the bactericidal action of blood serum and lvmph obtained from immune animals. Their demonstra- tions established the fact that immunity is due to a chemic substance, possibly an enzyme. But the origin and specific ac- tion of the chemicals in the production of immunity was not determined. The bacteriolytic substance of the body fluid called complement, was found to be destroyed by a temperature of 5B°C, 5. Ehrlich'’s Lateral Chain Theory —Ehrlich maitains — that every living cell contains an active central body and an indefin- ite number of marginal chemic groups or lateral chains desig- nated receptors. These receptors combine with and extend the nutriment to the central portion of the cell. The receptors are SS VETERINARY PATHOLOGY. b Fig. 64.—Uncinaria Canina, Cephalic extremity of female, magnified 350 diameters. a. Hooklets. b. Mouth cavity. c. Oecesophagus. Fig. 64a. Fig. 4b. Fig. 64a Section of body of female, magnified 100 diameters, showing the the ova to have formed in worm not to exceed five weeks old. a. Ovum. b. Intestine. Fig. 64b Caudal extremity of the female, magnified 100 diameters. also capable of combination with other substances as bacterial toxins. Toxic immunity is explained by Ehrlich as follows: Toxins are composed of two essential chemic groups which are desig- IMMUNITY. 0) nated haptophores and toxophores. The haptophore of the toxin has an affinity for the cell receptors. The union of the toxin haptophore and the cell receptor forms a medium through which the toxin toxophore passes to the central part of the cell where it exerts its action. Fig. 65.—Toxic Immunity. A) cell showing active central body and marginal chemic receptors, and toxin molecules surrounding It, Legend— a. Cell body. Cell receptors. Free cell receptors. Haptophore of toxin molecule. Toxophore of toxin molecule. Toxin molecule. Toxin molecule combining with free cell-receptor. Toxin molecule floating free and about to combine with a free cell-receptor. proeaos The toxin haptophores are not injurious except as they enable the destructive toxin toxophore to reach the central cell mass. Toxin toxophores in the absence of toxin haptophores are inac- 90 VETERINARY PATHOLOGY. tive. The result of the union with, or action of, the toxin toxo- phore upon a cell may produce immediate destruction of the cell or it may stimulate the cell to produce more receptors. The presence of toxin in the body fluids stimulates the body cells to produce receptors in excess. The increased receptors may remain in connection with the central body or they may become detached and float in the body fluids. Free receptors in blood serum is the essential active principle of antitoxin. Toxic im- munity may be better understood by giving an example. Example.—Tetanus is an intoxication disease due to the pro- duction of toxins by localized bacterial activity of the tetanus bacillus. Immunity to tetanus is dependent upon the neutraliza- tion of the tetanus toxin. The tetanus toxin is composed of hap- tophores and toxophores. The body cells possess receptors caba- ble of union with the tetanus toxin haptophores. The union of cell receptors and tetanus toxin haptophores enables the tetanus toxin toxophore to act upon the central mass of the body cell, thus stimulating them to form more receptors. The excess recep- tors become detached and float free in the body fluids and com- bine with the tetanus toxin haptophore, thus preventing the lat- ter from combining with the attached cell receptors. The te- tanus toxophores are not capable of combining with the central mass of the body cells except through the medium of tetanus toxin haptophores and if the tetanus toxin haptaphores are locked up with the detached cell receptors, the tetanus toxo- phores remain inactive and the animal is not inconvenienced by their presence and is immune. Toxic immunity is therefore dependent upon first, sufficient free receptors to lock up the haptophores thus inhibiting the action of the toxophore or second, upon the absence of hapto- phores. Bacterial immunity —From the phenomena observed in Pfeif- fers reaction Ehrlich has proposed an hypothesis in explanation of bacterial immunity. As previously stated, normal blood serum contains bacteriolytic substances (see humoral theory). Comple- ments are destroved by a temperature of 55°C. The blood serum of immune animals possess another substance, in addition to complement, not destroyed, by heating to 545°C. These are called amboceptors. According to Ehrlich, amboceptors, like toxins, are composed of two different combining groups, also designated haptophores and toxophores. The complemental substance of normal serum 1s not capable of action upon bacteria. The ambo- ceptor haptophore has an affinity for the comyimment of normal serum. The amboceptor toxophore has an affinity only for bac-- IMMUNITY. Oo] teria, but is not injurious to them. The amboceptor toxophore combined with or acting upon bacteria produces a condition favorable for the action of the combined amboceptor haptophore and complement, 1. e,, this enables the complement to cause dis- integration of bacteria. The amboceptor thus renders condi- tions favorable, 1. e., makes it possible for the bacteriolytic sub- stance, the complement, to exert destructive action upon bacteria, the amboceptor acting as middle man. CHAPTER IV. MALFORMATIONS. DEFINITION. ETIOLOGY. Intrinsic (heredity.) Extrinsic. Pressure, Amniotic Adhesion. Excessive Motion. Afodnutrinion, CLASSES. Style. Result of Arrested Developement. Result of Excessive Developement, Result of Transposed J isceral Orgnas. Result of Persistent Foetal Structures, Result of Mixed Sexual Organs, Double or Multiple. Symmetrical Duplicities. Complete (twins). Incomplete (double monster). Asymmetrical Duplicities. Multiple. During the embryonic stage of intra-uterine life the special- ized tissues and organs are formed. The foetal period is the time during which the structures formed in the embryonic stage grow and develop. At birth the young of a given species are of a definite shape, contour and type; the form or type which is most common is accepted as normal; and deviations from the normal are designated malformations, anomalies or developmental errors. Many new strains and breeds of stock have been the result of developmental errors becoming a fixed peculiarity. Thus the polled cattle, the Boston bull-dog, the Mexican (hair- less) dog, and the five toed chicken had their origin. Etiology—alformations may be brought about by pre- existing influences in the maternal cells, (internal or intrinsic causes), or from external influences (external or extrinsic causes). Internal or Intrinsic Causes—lInternal causes are inherited peculiarities, i e., heredity and atavismal influences. These are probably not the usual causes of malformation in domestic animals for malformed individuals are rarely used for brceding purposes. External or Extrinsic Causes of malformations are pressure, amniotic adhesions, excessive motion, insufficient or abnormal nutri- 92 MALFORMATIONS, 93 tion, infectious diseases, etc. External causes exert their in- fluence during the embryonic or formative period and they must act in a mild degree or death of the embryo and abor- tion follows Typical cpa oxmations are approximately of the same form and are usually produced by similar causes, Atypical mal- formations are variable in form and may be produced by a variety of causes. A complete description of all malformations is beyond the scope of general pathology. A general classification with a description and origin of the most striking malformations is all that will be attempted in this chapter. Malformations may be divided into two classes; Ist, Single malformations, and 2nd, Double or multiple malformations. Single malformations are those affecting a single individual. Single malformations may be grouped into five classes as fol- lows: Malformations resulting from; (a) arrested growth or development; (b) excessive growth or development; (c) trans- position of visceral organs; (d) persistent foetal structures; (e) mixture of sexual organs. ARRESTED DEVELOPMENT.—Malformations caused by arrested development may involve an entire individual or any part ot an individual. Arrested development of the entire individual results in the formation of an irregular, fleshy mass, called a mole, in place of the normal foctus. Moles may be carried in the uterus for the entire period of gestation. In some instances a mole and a normal foetus may be delivered at the same time. Moles have been observed in mares, more rarely in cows. Malformations resulting from arrested development of a part may be manifested by the entire absence of the part (aplasia), by underdevelopment of the part, (hypoplasia), or by a lack of union or fusion of tissue (schistosis and atresia). The fol- lowing malformations are the result of local aplasia. Acephalus. A name applied to a headless monstrosity. Acephalus is probably the result of amniotic adhesions. Atrichia. A defect in which there is no hair. This results from some disturbance of cutaneous development. Amyclus. A malformation in which the spinal cord is absent. Defects of the primitive streak or failure of production of the neural canal interferes with or prohibits the formation of the spinal cord and is the cause of amyelus. Acardia. A heartless monstrosity. Agastria. A malformation in which the affected individual 94 VETERINARY PATHOLOGY. has no stomach. This may be due to lack of sacculation of the embryonic gut. Acaudia. A malformed individual in which the defect con- sists in the absence of the tail. An acaudia fox terrier bitch was recently observed, her mother whelped one or two tailless puppies at each whelping. This bitch recently whelped an acaudiac puppy. Aprosopus. An individual having no face. aAgnathus. A term used to designate an individual in which the inferior maxilla is absent. This is common in lambs. Amelus. The name of a limbless or legless individual. Amelus is the result of arrested development of leg buds and is usually caused by unequal intrauterine pressure or amniotic adhesions. Monopygusamclus. A monstrosity in which one posteriot lez is wanting. This is due to arrested development of leg buds, probably due to amniotic adhesions. Dipygusamelus. The name of a malformed animal in which both posterior legs are absent. Result of arrested development of leg buds. AMfonothoracisamelus and dithoracisamelus are monstrosities in which one and both front legs are absent respectively. Apus. A name applied to a malformation in which the feet are absent. This may be the result of intrauterine amputation or amniotic adhesions. Jonopygusapits is ai individual in which one hind foot is wanting and a dipygusapus, an individual in which both hind feet are absent. Monothoracisapus, and dithoracisapus, are names implying the absence of one or both front feet. The following malformations are the result of under develop- nent or undergrowth. (Hypoplasia). Aficrocephalus, a term used to designate an individual hav- ing a diminished sized head, also used to designate the small head itself. This is probably the result of diminished nutrition to the head and anterior part of the body during embryonic and foetal development. Micro-cardia. A name applied to an individual having a small heart. This may be due to excessive pressure. Aicroophthalmia. A term used to indicate a malformation in which the eye or eves are smaller in size than the normal. This is probably the result of insufficient nutrition. Micrognathy. The name of an individual having a diminu- tive inferior maxilla. These are caused by undue pressure or insufficient nutrition. MALFORMATIONS. 95: Micromelus. A malformation so named because of the diminished size of all legs. This is caused either by diminished nutrition or undue pressure, The following are illustrations of arrested development mani- fested by absence of imperfect tissue union, thus producing fissures (schistoses), or resulting in fusion of parts that are normally separate (synactoses). TF issures of the body cavities are due to increased accumulation of fluids in internal organs, increased size of internal organs, prolapse of viscera before body walls have united, the presence of amniotic folds between cleft edges or lack of sufficient tissues to close the margins. Crantoschisis. The name of a condition produced by fail- ure of development and union of the cranial bones and resulting in a cleft. The meninges and in some instances the brain tissue may be exposed or there may be protusion of the menin- ges and also of the nerve tissue, thus producing meningocele or meningo-encephalocele, Calf. Fig. 66.—Cranioschisis Craniorrhachischists. A malformed individual so called be- cause of a fissure of the spine and cranium accompanied by exposure or protusion of the spinal cord and brain. “Rhachischisis. A condition in which there is a cleft of the spinal column. This malformation is usually the result of some defect in the margins of the neural groove. If the fissure ex- tends the entire length of the spinal column the resulting con- dition is called holoschisis. If the fissure does not extend the 96 VETERINARY PATILOLOGY. entire length of the spinal column, the condition is termed meroschisis (Gr. Meros—part, and schisis=splitting.) The spinal meninges may protrude through the spinal column fissure producing spina-bifida. A hernia of the spinal meninx that con- tains cerebrospinal fluid is termed spinal meningocele, and if the cord and meninges protrude, it is called a myelomeningocele. Fig. 67.—Cheiloschisis, Cheiloschisis, is the condition resulting from arrested de- velopment of the soft tissues covering the maxilla. This is the condition popularly termed hair lip. It is an inconvenience because it interferes with sucking the teat, the source of nutrient of the new born mammal. The defect may also involve the maxilla producing cheiliognathoschisis. Palatoschisis. A defect in which the palatine processes have imperfectly developed, thus leaving a fissure through which MALFORMATIONS. 97 Fig. 68.—Palatoschisis, there is free communication between the nasal and buccal cavities. This condition is commonly spoken of as cleft palate. Thoracoschisis. A condition resulting from failure of union of the thoracic walls. The thoracic viscera, the lung, heart and 69.—Abdominoschisis. FE: a gs. ” O8 VETERINARY PATILOLOGY. large vessels may protrude through the fissure thus producing ectopiacordis or ectopiacordispulmonaris. -tbdominoschisis, is the condition caused by failure of union of the abdominal parietivs. The condition is frequently accompanied by protusion of the abdominal viscera through the fissure. The abdominal fissure may involve only a portion of the cavity or it may be complete. LEctopia gastrium is the condition result- ing from protrusion of the stomach through an abdominal fissure; ectopia vesicae, protrusion of bladder, ete. Fig. 70.—Synophthalmia or Cyclonia. Synoynophthalmia, or cyelopia (Gr. Kuklops=mythical single eye monster), 1s a condition resulting from the fusion of the optical vesicles. Arrested development of the anterior cerebral vesicles allows the optical vesicles to contact and in some in- stances there is one large double eye centrally located or there may be two eyes occuring in a centrally located orbit. Cyclo- pia is usually associated with defects of the nose. Synactosis, is a general term denoting a condition caused by the fusion of parts or organs that are normally separate. Synmelus. A malformation caused by the fusion of two legs into one irregular member. Syndactylus. An individual having the digits fused or grown together. An illustration of syndactylism is the soliped hog. The soliped hog usually has two separate digits of three phalanges each and the ossa pedes are encased in a single hoof. Synmelusdipus. A malformation having fused legs and two feet. MALFORMATIONS. 99) Synmelusnonopus. An individual having fused legs and only one foot. Syamelusapus. A monster having fused legs and no feet. Synorchism. A malformed animal in which the testicles are fused. Arrested development may be evidenced by the nonappear- ance of the lumen in any of the natural hollow organs, (atresia). The mouth is formed by an ingrowth of the ectoderm and the buccal cavity extends inward until it meets the anterior clonga- tion of the embryonic gut. Later the partition separating the buccal cavity and the cavity of the embryonic gut is absorbed Fig. 71.—A condition of Solipedia in a hug. and thus the cavities become continuous. Jfailure of the exten- sion of the mouth cavity and its fusion with the embryonic gut constitutes the condition. tresia Oris. Atresia iridis, A defect in the eye due to the absence of an opening (pupil). Atresta oculi, a malformation in which there is no opening between the eyelids. Atresia anus is a condition in which there is an imperforate anus, that ‘is, there has been failure of union and fusion of the anal ingrowth and the rectal outgrowth, Atresia | anus: is of rather frequent occurrence and usually the defect is easily re- lieved. Atresia urethra. [mperforation of the uretnra, 1U0 VETERINARY PATILOLOGY. MALFORMATIONS RESULTING FROM EXCESSIVE DEVELOPMENT OR OVERGROWTH.—Excessive development is usually evidenced as a multiplicity of digits or phalanges though there may be multiplicity of any structure. Polydactylisia—The name applied to a malformed individual in which there is an excessive number of digits. Individuals having supernumerary digits are frequently observed, The condition is probably more frecuently observed in hogs than in other animals. Polydactylism, however, occurs occasionally in the ox and horse. Fig. 72.—Polydaetylism in a hog. Polymelusthoracicus.—This is a malformation in which the affected animal has one or more extra front legs. An interest- ing case was observed in a cow in which there was an irregular bone attached to the right scapula. and extending across the median line. This bone articulated with an irregular supernum- erary scapula and also with the spine of the left scapula. This irregular formed scapula articulated with another bone which was similar to a humerus on the distal end of which there was a rudimentary ulnar. The condition of supernumerary posterior legs is termed polvmeluspvegus. Dicaudis——An individual having two tails. This type of malformation is not very common. It is probably the result of MALFORMATIONS, 101 Fig. 73.—Prognathism, common name “undershot.” a division or cleavage of the caudal segments during embryonic formation. Multiplicity of internal organs is occasionally observed. Thus several cases of partially double spleens have been reported. An interesting case of malformation was observed in a hog, the defect 102 VETERINARY PATHOLOGY. consisting of a double penis. This individual may have been called a dipenis. Malformations from excessive growth may be applied to the entire animal when it is excessively large (giants). Malforma- tions resulting from overgrowth of a part are frequent; thus one foot, one leg, the head or any other part may be overgrown. Darwin, (in Plants and Animals under Domestication), men- tions a cat that he observed which had incisor teeth one and one half inches in length. Fig. 74.—Schistosis melus anticus or dimelus aaticus—Male, (Drawing made from a photograph.) TRANSPOSITION OF VISCERAL ORGANS, (situs viscerum inverstts-. Very rarely animals are observed in which the visceral organs are re-arranged, i. e., those organs that normally occur on the left side of the body are found on the right side. A sheep in prime condition was observed which was normal in appearance except its head was turned slightly to the left and the atlas was ankylosed to the occipital, thus giving it but little vertical motion. The right shoulder was anterior to the left. The vis- cera were entirely reversed; the heart was hanging toward the MALFORMATIONS. 103 right: the four compartments of the stomach were transposed, the rumen being on the right side, and the spleen being in con- tact with the right side of the diaphragm; the liver was on the left side and the right kidney was posterior to the left which was swinging free as the right usuaily does. Transposition of visceral organs probably results from an irregularity of the allantoic veins and their continuation. In normal development the right vein atrophies and the left vein becomes larger in early embryonic life and if for any reason the left vein atrophies and the right vein becomes longer then the visceral organs tend to develop in the reverse position. : PERSISTENT FOETAL STRUCTURES,—AIl the malformations are grouped into this class that retain embryonic or foetal structures abnormal to extra-uterine forms of life. Cryptorchids—(Gr. Kruptein—to hide and orchis-testicle) are probably the most frequent malformations resulting from the persistence of a foetal structure. The testicles of domestic ani- mals are formed within the abdominal cavity during embryonic life and later migrate, except in fowls, birds, ete., to their per- manent position in the scrotum. Cryptorchids are animals in which the testicle was properly formed, but did not descend to the scrotum. Dr. DeWolf carefully inspected 4671 male hogs and found 28 single and 7 double cryptorchids. Cloacal Persistence —During embryonic life the rectum and urogenital tract terminate in one common cavity known as the cloaca. The cloaca persists throughout life in the avidae, but not in mammalia. H. Brassy Edwards, M. R. C. V.S., reported a case in the veterinary Journal of an imperforate anus in a brindle bull bitch pup 10 days old. There was no trace of an anus and the prominence usually felt in the perineal region of imper- forate anus was also absent. On operation the rectum and uterus were found to be fused, thus producing a cloaca. Dr. P. Phillipson of Holbrook, Nebr., reported a colt in which there was a cloacal formation. In this case the floating colon fused with the uterus and the vagina was a common opening of the digestive tract and the genito-urinary tract. Cervical ectopia cordis—This is the name of a malformation in which the heart is located in the cervical region. The heart is normally formed in the cervical region and if the anterior thoracic wall closes prematurely, the heart remains in that re- gion. MIXTURE OF SEXUAL ORGANS, HERMAPHROpITISM.—The sexual glands, ovaries and testicles, and the external genitals, of both 104 VETERINARY PATHOLOGY. Ectocardia. 75— Fig. sexes, are derived from four similar embryonic structures. The influence or factors determining sex are not known. During embryonic development the sexual determination is not distinct, MALFORMATIONS, 105 the individual possessing more or less complete sexual organs typical of both the male and the female. Animals im which there is a combination of sexual organs are termed hermaphro- dites. According to the development of sexual! organs, herma- phrodites are designated as true and pseudo or false herma- phrodites. A true hermaphrodite possesses secreting sexual glands of both sexes, i. e., they have secreting ovarian and testicular tis- sues. The external genitals of the true hermaphrodite may be bisexual or unisexual. True hermaphrodites are rare, and fer- tility of such animals is doubtful. True hermaphroditism may be lateral, bilateral or unilateral. Lateral hermaphroditism is the condition in which there is an ovary on one side and a testicle on the other. The follow- ing example illustrates this type. The animal was a two year old bovine and had an ovary suspended by the left broad liga- ment and a testicle suspended by the right broad ligament. The two glands had their normal appearance, typical of ovarian and testicular tissues. This type of hermaphroditism is rare. Bilateral hermaphroditism is typified by the presence on both sides of an ovary and a testicle, or a single organ on each side containing ovarian and testicular tissues. This type of her- maphroditism, also is rare. Unilateral hermaphroditism is characterized by the presence of a single organ, as an ovary or testicle on one side and an ovary and testicle on the other side or an organ containing ovar- jan and testicular tissue on one side. This type is not common. Pseudo or false hermaphrodites are individuals having one distinct type of sexual glandular tissue and in which the exter- nal genitals partake of the nature of both sexes. This type of malformation is more common in the male and is usually the result of persistence of Miillers canal and the further develop- ment of the uterus and Fallopian tubes. In pseudohermaphro- ditism the testicles are usually retained in the abdominal cav- ity. There are usually Fallopian tubes, vagina and uterus, the completeness of which is variable. The appearance of the testt- cle is variable according to the development of the female external genitals. Pseudohermaphroditism is much less fre- quent in the female than in the male. 7 A rather well marked case of a pseudohermaphroditic horse was obtained and carefully observed for some time after which it was destroyed and the type and relation of the sexual organs were determined by dissection. In this animal the head and neck while not decisive of either sex in general rather favored 106 VETERINARY PATHOLOGY. the male in conformation. There was quite a well marked vulva and the much elongated clitoris projected about four inches postero-inferiorly and closely resembled a penis. The uterus was quite rudimentary and the reproductive glands were located near the normal location of the internal inguinal ring and had very little resemblance to either testicle or ovary. Microscopic examination did not solve the difficulty for the glands were a conglomerate of small cysts. The mammary gland was fairly well developed. Double or Multiple Malformations—Under this caption those malformations will be considered that involve two or more individuals developing simultaneously. Marchand’s classifica- tion of duplicate monsters is adhered to in the following discus- sion. The entire subject of duplicate monsters may be subdi- vided into 1st, symmetrical duplicity, 2nd, asymmetrical dupli- city, and 3rd, multiplicity. SYMMETRICAL bupLicity.—The individuals, in symmetrical duplicity are, in the beginning, similar and symmetrical. Each of the symmetrical duplicates is derived from separate, similar, equal anlagen of a single fertilized ovum or bisection of a single anlagen. This class of malformations may be divided into two groups :—viz., complete and incomplete duplicities. Complete Duplicity—Complete duplicates are in the begin- ning alike and complete and the individuals may remain sep- arate thus forming twins, (free duplicities,) or they may be united, thus forming double monsters. Twins, (free duplicates), develop in a single chorion though each individual usually has a separate amnion and _ allantois. Monochorionic duplicates may develop equally or unequally. depending upon the division of nourishment. The above dis- cussion primarily applies to uniparous animals. However, by varying the number it is equally applicable to multipares. Twins also result from simultaneous fertilization of two ova. Double monsters are mono-chorionic duplicities in which the bodies are united. The two bodies may be equal or unequal in size, depending upon the distribution of nourishment. Double monsters are the result of partial fission of a fertilized ovum, partial fusion of two separate anlagen of a single ovum, or par- tial fusion of two fertilized ova. The attachment of the two bodies of the double monsters may be posterior, middle or anter- ior. Posterior union may be dorsal or ventral. In the former the union occurs at the pelvis, and the dorsal surfaces of the bodies are usually in apposition, such a monster is called a pygopagus. MALFORMATIONS. 107 Pygopagi have two umbilical cords which fuse to torm a single cord; coccyx and sacrum are single, rectum and anus usually single; spinal cord double anteriorly, fused posteriorily form- ing a single filum terminale; urogenital system usually double. Ventral posterior union may be confined to the pelvic region, (ischiopagus), or it may extend anteriorly to and including the thoracic cavity, (thoracisischiopagus). The two bodies in ven- tral posterior union are so united that their venter surfaces are in apposition. Ischiopagi, usually have a single umbilicus and cord; pelvic organs may be single or multiple; there is usually no anus. If one of the bodies is small or rudimentary, it is desig- nated a parasite, (1schiopagusparasiticus). Thoracoischiopagi, may have single or double thoracic viscera; the abdominal vis- cera are usually double. Middle union in double monsters occurs on the venter sur- face from the umbilicus and extends anteriorly. There is usu- ally a single umbilicus; the abdominal viscera is usually double; thoracic viscera single or double, depending upon the area of union; middle union may occur at the xiphoid cartilage, (xipho- pagus), involve the entire sternum, (sternopagus), or the entire thoracic venter surface, (thoracopagus), xiphopagi may survive, the “Siamese Twins,’ were of this type. Thoracopagi are fre- quently unequal in size, the smaller one being designated as a parasite. Anterior union may be dorsal or ventral or the union may be on the anterior surface of the head. Dorsal, anterior union rarely occurs, the attachment being on the frontal region. These malformations are designated Craniopagi. Ventral anterior union occurs occasionally. The union in this type is along the venter cervical region and extends onto the venter thoracic re- gion. The sternum and oesophagus are single; larynx, trachea and stomach may be single or double; intestine double; there may be two faces or the faces may be fused. Fused-face mon- sters resulting from union of the venter anterior cervical or cephalic regions are called syncephali. Incomplete Duplicity is the name applied to those malforma- tions in which the greater part of the body is single, duplica- tion occurring in only a part. The duplicity may involve any part. These malformations are not easily differentiated from malformations resulting from multiplicity of parts as polydacty- lism. ASYMMETRICAL DUpLIciry are those malformations result- ing from the development of two separate, dissimilar, unequal anlagen of a single ovum, the development of a fertilized polar 108 VETERINARY PATHOLOGY. Fig. 77.—Dicephalic Calf. MALFORMATIONS. lu) body or the development of an isclated group of segmentation cells. In asymmetrical duplicity one body is rudimentary or under-developed, (the parasite), and the other body develops normally or nearly so, (the autosite). The parasite always remains attached to the autosite or is included by it. Parasitic duplicity may occur in any region. Thus the parasite may pro- ject from the orbit, mouth, shoulder or it may be included in the thoracic or abdominal cavities. MULTIPLICITY is the name applied to designate the develop- ment of more than two separate individuals in a single chorion. Multiplicity is of rare occurrence. One single case has been authentically reported in the human in the form of a tricephalus. CHAPTER V. CIRCULATORY DISTURBANCES. Normal blood circulation is dependent upon the rate, rhythm and force of the heart, the caliber of the blood vessels and the resistance offered by them and the quantity and the quality ot the blood. Variation of Heart Action.—A marked variation in the heart activity results in imperfect circulation. Depressed wr dimin- ished heart action is more common than increased heart action. Diminished functional activity is most frequently caused by in- flammation of the endocardium, myocardium, epicardium or per- icardium. Valvular stenosis and valvular insufficiency are the result of endocarditis. Myocarditis diminishes the activity of the heart and if the intammation is long continued the muscle cells are destroyed and replaced by fibrous tissue thus per- manently impairing the force of the heart. Inflammation of the epicardium and pericardium may be accompanied by volumin- ous exudation which distends the pericardial sac and produces sufficient pressure to hinder diastole, or the exudate may be- come coagulated and later organized attaching the sac to the surface of the heart and thus hindering cardiac systole. Cardiac activity may be diminished by the collection of fluid in the pleural cavity, malformed thoracic cavity, tumors, occlusion of coronary arteries, fatigue and thrombic formation upon the cardiac valves. Diminished cardiac activity results in a dimin- ished quantity of blood being sent out from the heart and an accumulation of waste products in the tissues. Increased functional activity of the heart is usually only tem- porary excepti.g in those animals affected with cardiac com- pensatory hypertrophy The most common cause of increased cardiac activity is reflex stimulation. Increased activity due to reflex stimuiation may terminate in exhaustion and syncope in a relatively short time. Increased functional activity. due to a cardiac compensatory hypertrophy resulting from increased resistance as in emphysema, chronic nephritis, etc., may result in permanent over action of the heart. Anatomical changes in the cardiac-structure, as hypertrophy, fatty degeneration, fragmentation, fibrous formation, or necrosis 110 CIRCULAR DISTURBANCES, iad may be evident when the functional activity of the heart is varied, Vascular Variations—The amount of blood passing into or out of a given organ is determined by the caliber of the blood vessels, provided the heart action and general blood pressure remain normal. Variations in the caliber of normal blood ves- sels depend primarily upon the response of the vessel muscu- lature to vaso-motor stimulation, Blood pressure is dependent upon the elasticity of the arteries and the force of the heart. In general, pathologic vascular variations are the result of, first, disturbed arterial elasticity; second, the maintainance of the normal caliber of the vessels and; third, the nermeability of the vascular walls. Arteriosclerosis is a condition in which the elasticity of the vessel walls is lessened or destroyed. In the production of arteriosclerosis there is vascular dilatation succeeded 1 by suben- dothelial fibrous formation which continues until the lumen of the dilated vessel is reduced to its normal size. The hyper- plastic fibrous tissue may later become calcified. Sclerotic arteries are thick, stiff and nonelastic. Sclerosis is most com- mon in arteries although it occurs in veins. The vascular caliber may be diminished by muscular con- traction or by hypertrophied vessel walls. In animals affected with chronic nephritis there is contraction of the systemic arteries resulting in compensatory cardiac hypertrophy. Arterial constriction is also common in the peripheral vessels of animals affected with carbon dioxide poisoning. Local diminution of vascular caliber may be produced by parietal thrombi. The vascular caliber may be increased by paralysis of the vaso- motor nerves a condition which is sometimes observed in ani- mals that have received injuries in the cervical region. Increased permeability of vessel walls usually results from insufficient nutriment to the vascular structures and occurs most frequently in small vessels, i. e., capillaries and venules. Increased permeability usually accompanies venous hyperemia although it may exist independent of variations in the quantity of blood. Thus oedema is common in hydremic individuals. Variations in Quantity and Quality of Blood.—The quantity of blood in a part is determined by the caliber of the supplying vessel and by the blood pressure. Acute general anemia re- sults in a diminished blood pressure which, if not corrected in a short time, terminates fatally. Chronic general anemia is accompanied by a slightly diminished blood pressure and a re- tarded blood current. 112 VETERINARY PATHOLOGY. The most important variations in the quality of blood that concerns the student of general pathology are due to the varia- tions of the percentage of water contained. Hydremia is ac- companied by disturbances of the renal function and by oedema. Anhydremia is productive of a slow weak pulse and the sec- ondary changes resulting therefrom. Excess of carbon dioxide or urea in the blood stimulates the vaso-constrictor nerves thus causing arteria! contraction. Hemorrhagic diathesis or hemophilia is an inherited condi- tion in which there is little or no tendency for coagulation of blood. The cause of this condition is the absence of some blood constituent essential to coagulation. HEMORRHAGE. DEFINITION. ETIOLOGY. Ruptured vessel. Rhexis or diabrosis. Increased permeability. Diapedesis. Predisposition (hemophilia). MARIBTIES. Location. Tissue. Petechia (flea bite) pin point. Ecchymosis (over-How) from pin point to size of dime. Suggillation (swelling) bruise. Effusion, Hematoma (blood tumor). Infarction. Surface—Skin, mucous, membrane, serous membrane, Epistaxis. Hematemesis. Hemoptysis. Hematuria, Hematidrosis. Hematometra.. FHematocele. AMetrorrhagia, Hemathorax. FRemocoelia, ete. Vessels. Cardium. Arteries. Tveins. Capillaries. APPEARANCE. Macroscopic. Microscopic. Tissue hemorrhage. Clot: EFFECTS. Rate of outflow. Location. Secondary chance of extravasate. CIRCULAR DISTURBANCES, 113 Hemorrhage is the escape of blood from a vessel, (capillary, vein, artery or heart.) Etiology.—Some animals are predisposed to hemorrhage (hemophilia). Hemorrhagic diathesis or hemophilia is an in- herited condition in which there is little or no tendency for coagulation of blood. The cause of this condition is the ab- sence of some blood constituent essential. to coagulation or rupture of vessel wall, resulting from diseased vessels as ulceration, thus producing hemorrhage by dtabrosis, or in Fig. 78.—Petechial hemorrhage, Kidney hog cholera lesion, a. Hemorrhagic area. e Glomerulus engorged with blood. b. Normal kidney tubule. creased pressure and traumatism, thus producing hemorrhage by rhexis. The permeability of the vessel walls may be sufh- ciently increased by pressure or disease so that hemorrhage takes place by diapedesis. The escaped blood, 1. e., the ex- travasate, may flow upon the surface of the skin, serous or mucous membranes, or into the tissues. TISSUE HEMORRHAGES may vary greatly in amount and are designated by the following terms, petechia, ecchymosis, sug- gilation, effusion, infarction and hematoma. Petechiae are small sharply defined hemorrhagic points and are probably caused by bacterial products in the blood. 114 VETERINARY PATHOLOGY Ecchymoses are hemmorrhagic spots larger than petechiae and less sharply defined caused by ruptured capillaries or precap- illaries. Suggillations and effusions are large indefinable hemorrhagic areas, caused by bruising which ruptures the small vessels. Hemorrhagic infarction is a hemorrhage into an anemic area. This is not a hemorrhage as ordinarily understood for the blood is eh wdc See Fig. 7.—Hematoma, caused by rupture of spur vein, within the vessels and escapes into the anemic area because of the ciminished pressure. A hematoma is a circumscribed collection of extravasated blood in the tissues and is usually the result of hemorrhage from an artery. SURFACE HEMORRILAGE is designated according to its origin, thus: Epistaris is hemorrhage from the nasa? mucous theribrame and is quite common in acute nasal glanders. Fematemesis is hemorrhage from the stomach and is ob- served in animals poisoned with arsenic and those afflicted with gastric ulcer or gastric carcinoma. FAemoptysis is hemorrhage from the lungs. It may be the result of excessive exertion, abscess formation, tuberculosis, etc. CIRCULAR DISTURBANCES, 115 Hematuria is hemorrhage into the urinary tract or bloody urine. The blood may escape from the kidney, and if so there will be tubular casts discernible on microscopic examination of the urine; it may come from the ureter or bladder, and would then be thoroughly mixed with the urine; or it may have its ortgin from the urethra and would not be mixed with the urine but would usually precede it. Hematidrosis is hemorrhaga from the surface of the skin and is the so-called sweating of the blood and is caused by in- creased permeability of cutaneous capillaries. Enterorrhagia is hemorrhage from the intestinal mucosa and may be differentiated from hematemesis by the appearance of the extravasate in the feces. The extravasate in hematemesis has the appearance of coffee bean grains in the feces while the en- terorrhagia extravasate retains the hemoglobin color and is not broken up into granules. (The coffee bean appearance of blood extravasated into the stomach is due to the action of the hydro- chloric acid of the gastric juice.) Enterorrhagia is caused by infection as in anthrax and by caustics. Hematometra is hemorrhage from the uterine mucosa the extravasate being almost entirely retained in the uterus. This is usually caused by improper removal of retained placenta. Metrorrhagia is hemorrhage from the uterine mucosa and the extravasate passes out of the uterus. Menstruation in the hu- man is an illustration of metrorrhagia. Hemococlia is hemorrhage into the peritoneal cavity and is caused by rupture of the peritoneum or some abdominal organ. Hemothorax is hemorrhage in the pleural cavity, and is caused by ruptured pleura as a result of fracture of a rib, etc. Hematocele is hemorrhage into the tunica vaginalis cavity. This mav be the result of laceration or rupture of the tunica vaginalis testis. Effects—The effects of a hemorrhage depend upon the quantity of blood lost and the location and secondary changes of the extravasate. In health the vascular system practically maintains a constant blood pressure by accomodating the capacity of the blood channels to the volume of the blood. The quantity of blood that an animal may loose without be- ing seriously affected varies according to its age and health. The blood tissue of the horse has been estimated at from 1-16 to 1-12 of the total body weight. One-tenth of the esti- mated total amount of blood in the body has been withdrawn from horses used in the production of anti-toxin once every two weeks for from six to eight months without injurious results. lio VETERINARY PATHOLOGY. From 1/, to % of the volume of the blood in the body may be withdrawn at once and the animal recover. Hemorrhage from a small vessel has little effect upon the welfare of the body for the quantity lost is immediately restored from the lymph and other fluids of the body. Thus there may be a constant hem- orrhage from the digital artery of the horse for twenty-four hours without injurious consequences. A sudden large loss of blood diminishes blood pressure and this results in imperfect action of the heart valves. The blood is churned back and forth, becomes mixed with air and this frothy mass accumulates beneath the valves and prevents their closure. Hemorrhage is serious when it occurs in the more delicate or the more highly organized tissues. Thus the amount of extravasate into the cerebrum may be very small and yet pro duce sufficient disturbance to destroy life, while the same amount of extravasate into the muscles of the thigh, forearm, etc., would probably not be observed. The extravasation of blood into one of the body cavities, as the pleural or peritoneal cavity, will be partially absorbed as entire blood before it beecomes coagulated, the remaining un- absorbed portion will be in part disintegrated and carried out by the leucocytes and the remaining portion will finally be- come organized and remain as a mass of fibrous tissue. If the loss of blood is not sufficiently large to materially diminish the blood pressure and the extravasate remains free from infection there will be very little inconvenience from the hemorrhage; but if the extravasate becomes infected the outcome will be more serious. If the extravasate is into some important tissue the secondary changes will be of more consequence than when in the body cavities. There is a natural tendency for self arrest of hemorrhage, because, Ist, blood pressure is diminished during hemorrhage and thus coagulation is favored; 2nd, the endothelium of the injured vessels becomes roughened and thus thrombic forma- tion is favored; and 3rd, fibrinogen is liberated from vascular endothelium and thus the coagulation of the blood is favored. CIRCULAR DISTURBANCES, 147 LYMPHORRHAGIA. DEFINITION. (Extent of lymphatic system). (Lyntph transdate quantity determined by blood pressure). ETIOLOGY. Ruptured vessel or space. LOCATION. Surface, because of lymph spaces and low pressure. Thoracic duct. APPEARANCE. Macroscopic. Microscopic. EFFECTS, Lymphorrhagia is the escape of lymph from ruptured lymphatic vessels. The lympathic system in general is the con- necting system between the blood capillaries and the jugular vein. In this system lymph is that portion of the blood which passes, through (or is secreted by), the capillary walls into the perivascular spaces and consists of plasma diluted, leucocytes. and usually contains considerable waste material. Lymph varies in its composition depending upon the source, location and condition of the surrounding tissue. The lymph of the lacteal system depends upon the kind of food-material di- gested and the length of time since its ingestion. Etiology.—Lymphorragia is the result of laceration or rupture of the lymphatic channels. Because of the low pressure within the lymphatic vessels, lymphorrhagia takes place only upon surfaces or into the body cavities. Lymphorrhagia onto a surface, if long continued, results in the so-called lymphatic fistula. Rupture of the abdominal portion of the thoracic duct accompanied by the escape of its contents into the peritoneal cavity produces the condition known as chylous ascites. Chylous ascites is differentiated from abdominal dropsy or ascites proper by examination of the accumulated fluid. The fluid of chylous ascites and lacteal fluid are practically identical in composition. Ascitic fluid proper is diluted lymph and con- tains no evidence of chyle or lacteal fluid. Lymphorrhagia may also occur into the pleural cavity as a result of the rupture of the thoracic portion of the thoracic duct. The effects of lymphorrhagia depend upon the extent, loca- tion and length of duration of the process. Extensive lymph- orrhagia from a large lymphatic vessel depletes the body be- cause of the loss of food substances, albumin, etc., in the lymph. Lymphorrhagia from the thoracic duct, especially into the peritoneal cavity, is serious because of the loss of food. 118 VETERINARY PATHOLOGY. OEDEMA, DROPSY OR HYDROPS. DEFINITION. ETIOLOGY.. Increased production. Increased permeability (Cohnhewn.) fncreased pressure. OBSTRUCTED OUTFLOIW. , Valvular insufficiency or stenosis (cardiac). Gravid uterus. Tumor, Abscess, Ligature, etc. LOCATION. Peritoneal cavity (ascites). Thoracic cavity (hydrothorax). Pericardial cavity (hydropericardium). Arachnoid space (hydrocephalus external). Lateral ventricles (hydrocephalus internal). Tunica vaginalis cavity (hydrocele). Subcutaneous lymph spaces (anasarca) (in legs only, stocking). APPEARANCE. Macroscopic. Microscopic. EFFECTS. Oedema, dropsy or hydrops is the accumulation and retention of lymph in the lymph vessels and spaces. Lymph is the conveyor of metabolic substances to and from all tissues of the body except those directly supplied by the blood capillaries. The quantity of lymph in the lymphatic channels is determined by the permeability of the capillary walls and the rapidity of lymphatic absorption. In health there is a balance between the transudation of lymph from the blood vessels and its absorption into the lymph vessels. In oedema there is either a larger amount of lymph transuded or a smaller amount absorbed. Etiology.—The causes of oedema may be: 1. Increased transudation which may be caused by (A) Increased permeability (or secretory function) of the capillary walls, thus allowing an increased amount of fluid to escape from the blood. (B) Hyperemia: which produces) an in- creased intracapillary pressure resulting in sufficient injury to the endothelial lining to allow an increased outflow of plasma. Passive hyperemia is more frequently associated with oedema than active hyperemia. Thus, tricuspid stenosis or tricuspid insufficiency is usually associated with general dropsy. “Stocking” is an oedema usually resulting from venous hyper- emia. 2. Obstructed outflow of lymph. Swollen lymphatic glands, the result of inflammatory disturbances or neoplasms, and CIRCULAR DISTURBANCES, 119 external pressure hinder the passage of lymph and hence favor its accumulation. As the anastomoses of lymph channels is quite complete the obstruction of the outflow of lymph is a minor cause. Varieties of oedema according to location are as follows:— Fig. 80.—Dog with Ascites, a result of an hepatic tumor. Ascites: an abnormal accumulation of an oedematous fluid in the peritoneal cavity usually resulting from obstructed portal circulation. Hydrothorax, and abnormal accumulation of oedematous fluid in the pleural cavity or cavities. It is usually unilateral in the horse and is caused by obstruction of the internal thoracic vein. Hydropericardium; and abnormal accumulation of oedematous fluid in the pericardial sac. This variety is very rare as a primary condition. It is caused from venous obstruction of cardiac vessels or vessels of the cardiac sac. Hydrocele: an abnormal accumulation of an oedematous fluid within the vaginal tunic, e. g., the so called “water seed”, caused by adhesion of the vaginal tunic in the inguinal canal which is usually the result of improper castration. Hydrocephalus: an abnormal accumulation of oedematous fluid in the serous cavities of the brain or its meninges caused by venous hyperemia. Thus external hydrocephalus is an 120 VETERINARY PATHOLOGY. affection of the subarachnoidean spaces and internal hydroce- phalus an affection of the ventricles of the brain. Anasarca: an abnormal accumulation of oedematous fluid in the subcutaneous areolar tissue. Fig. 81.—Subcutaneous Oedema, caused by valvular inesutliciency. Appearance. Macroscopic—Oedema of the body cavities results in their distention and in the displacement of the normal cavity contents as a result of the accumulated fluid. The serous membrane becomes discolored. Oedematous fluid is thin, water- like, pale yellow, or colorless, contains less albumin and is less coagulable than either blood serum or inflammatory exudate. An oedematous tissue is swollen, flabby, soft and pits upon CIRCULAR DISTURBANCES, 121 pressure, and if incised, a watery, pale straw colored fluid es- capes. Microscopic—The intercellular spaces are increased in ex- tent, hence the cells are farther apart than normal and may be undergoing degeneration or atrophy, or be swollen and con- tain vacuoles. Effects.—The effects of oedema vary according to the causa- tive agent, the tissue involved, and the length of duration of the process. If the etiologic factor is capable of reproducing or increasing in quantity, as infectious agents (Bacillus of Malignant Oedema), there is more extensive tissue destruction than when the oedema is produced by other agents. Oedemua of the meninges of the brain or spinal cord may result in degeneration and destruction of the nerve cells and death of the diseased animal. On the other hand oedema of the sul- cutaneous tissues of the metacarpal or metatarsal region is of little consequence. Oecedema of brief duration docs not, as a rule, produce permanent injury to the involved tissue, but an oedema of long standing is of serious consequence because of the extensive hydropic infiltrations of the cells of the affected tissue and because of the constant depletion of the system. Hydropic degeneration, thrombosis and necrosis are frequent sequellae of oedema. 122 VETERINARY PATHOLOGY. THROMBOSIS. DEFINITION. ETIOLOGY. Injured endothelium, Mechanical—Artery forceps. Atheromatous degeneration, Insufficient nutrition, Foreign bodies—Parasites, etc. Retarded rate of blood flow. Increased coagulability of blood, PROCESS OF FORMATION. LOCATION. Occurs in all vessels, more prevalent in veins and heart. VARIETIES OF THROMBI. Color, Red. White. Mixed. Extent. Partial, Lateral. Parietal (annular). Complete (obstructive), EXTENSION OF THROMBI. APPEARANCE. SECONDARY CHANGES OF THROMBI, Decolorization, Softening. Simple. Infective. Organization. Calcification. EFFECTS DEPEND UPON. Vessels obstructed. Secondary changes of thrombi, Thrombosis is the condition resulting from a coagulation of blood within the vessels or heart during life. A thrombus is the coagulated blood within a living vessel. The accumula- tion and adhesion of leucocytes on the interior of vascular channels is also spoken of as a thrombus. The term thrombus should not be confused with a coagulum or a clot. A coagulum is coagulated blood within a vessel formed after death of the vessel wall, and a clot is coagulated blood formed outside of the vessel. Tlrombosis is of quite common occurrence. It is occa- sionally a sequel of parturition. Thrombic formation of one or both of the iliac arteries of the horse is a demonstrated cause of lameness. Thrombo-embolic colic of the horse is caused by thrombosis of the anterior mesenteric artery. The appearance of ante-mortem clot is familiar to all post-mortem examination observers. Intravenous or intra-arterial injections are probably always succeeded by thrombic formation at the he Ty oe (ay Bs eee AS pee 2 90 Oy Gy [i ” . BED & Cor Fy oes: < "2G ° : eS ix ee ie eps age | EBS aw Fig. 87.—Hyperemia of sidney, showing engorged capillaries, Aicroscopic-—Tissues affected with arterial hyperemia con- tain dilated arteries and capillaries, the lymph spaces are en- gorged with lymph, the tissue cells may be considerably swollen and diapedesis may be noted. Effects—The effects of arterial hyperemia depend upon the cause, degree, and duration and organs affected. Arterial hyperemia caused by infective agencies is more serious than if caused by other means. Arterial hyperemia of a sthenic type is usually succeeded by inflammation and asthenic hyper- emia may terminate in recovery. CIRCULAR DISTURBANCES, 137 Arterial hyperemia of short duration is tess serious than it would be if long continued, thus, active pulmonary hyper- aemia is occasionally aborted in the horse and such animals are usually ready for service in 24 to 48 hours, but if active pul- monary hyperemia continues for 24 hours it is succeeded by inflammation (pneumonia). Arterial hyperemia varies in different organs. Affections of the more highly organized structures are usually more seri- ous. Physiologic arterial hyperemia is a condition in which there is an increased amount of blood flowing into a tissue be- cause of increased physiologic demand, thus during gastric di- gZestion an excess of blood passes to the stomach through the gastric arteries. Therapeutic arterial hyperemia, when properly produced in a diseased part, results in (a), diminished pain, (b), resorp- tion of inflammatory exudate, hemorrhagic extravasate, and cedematous transudate, (c) increased nutrition, thus by the al- ternate use of cold and hot applications an arterial hyperemia is produced and is of value in strained tendons, bruises, ete. Pathologic arterial hyperenua, may produce hypertrophy, hyperplasia and permanent arterial dilatation. Excessive de- velopment of a part (hypertrophy or hyperplasia) may result from a long continued active hyperemia as in thickening of the skin as a result of continued application of blistering agents. but arterial hyperemia is as a rule of short duration for it csually terminates in recovery or is succeeded by inflammation CHAPTER VI. INFLAMMATION. DEFINITION. GENERAL CONSIDERATION OF STIMULI AND REACTIONS. ETIOLOGY. Non-infective. Mechanic. Thermic. Electric. Chemie. Infective. Non-suppurative. Suppurative. FACTORS CONCERNED IN INFLAMMATION, (Phenomena.) Vascular, Constriction of vessels. Dilatation of vessels. eleceleration of rate of blood flow. Retardation of rate of blood flow and leucocytic margination, Oscillation of blood in the wessels and diapedesis. Stasis. Exudation, Exudate. Composition. Physic. Chemie. Histologic. Varieties. Serous, Fibrinous. Hemorrhagic. Factors determining quality and quantity, Cause of inflammation. Condition of animal. Location of process and of tissue affected. Significance of the exudate. Increased amount of nutrition to the affected part.— Pilutes, counteracts, neutralizes or destroys the irritant, Circumscribes the inflammatory process. Chemotaris. Phagocytosis. THE SIGNS OF INFLAMMATION. Redness welling. Increased temperature. Pain. Impaired function. EFFECTS UPON THE TISSUE INVOLI'ED. Degeneration. Parenchymatous. Fatty. Mucoid, Serous. alinylotd, FTyaline, Necrosis. Regeneration or proliferation. 138 INFLAMMATION, 139 THE KINDS OF INFLAMMATION. Etiology. Stuple. Iufective. Non-sup purative. Suppurative. Surface. Sub-surface, Exudate, Serous, Fibrinous, Hemorrhagic. Tissue, Parenchymatous. Interstitial. Time, activity and results, elcute. Chronte. Miscellaneous, Catarrhal. Purulent, Ulcerative, Vesicular. Pustular, Proliferative. Specific. TERMINATION. Resolution. Tissue proliferation. Dissolution. CONCLUSIONS. Inflammation is a name applied to a group of pathologic processes including circulatory disturbances, retrogressive and progressive tissue changes. The term inflammation is difficult to define because of the several factors entering into the process and of the variation of each factor. It may be defined as the reaction of a living animal tissue to an irritant. A stimulus is anything that produces action in a living tis- sue. An irritant is anything that produces excessive stimulation in a responsive tissue. Stimuli and irritants differ only in degree. Mild friction of the skin is a stimulus to that structure. When the friction is intensified and the cutaneous function is overstimulated the friction becomes an irritant. All living tis- sues respond to stimuli and likewise to irritants. The response or reaction of a living tissue to an irritant, i. e. excessive tissue stimulation, accompanied by circulatory disturbances and by destructive or proliferative tissue changes, constitutes the pro- cess known as inflammation. The general phenomena of in- flammation will be better understood if some preliminary con- siderations of the reaction to stimuli are first discussed. General Consideration of Stimuli and Reactions.—It is a 146 VETERINARY PATHOLOGY. well known fact that all living things (organisms) respond to stimuli, A stimulus is that which excites or produces a tem- porary increased vital action, or it is any substance or agent capable of producing activity in a living tissue or producing an impression upon a sensory organ. The extent or degree of response to a stimulus is directly proportional to the organi- zation and complexity of the tissue and especially those tissues which are: (a) capable of being stimulated; (b) capable of trans- mitting an impulse; and (c) capable of interpreting the impres- sions produced by the impulse. The following discussion of response to stimuli is confined to animal tissues because inflam- mation affects animals only. Protozoa, although of the simpliest structure, consisting of a single cell, respond to the various stimuli. They respond to light. Thus, if a portion of a cover glass preparation of living amoebae be exposed to intense light, the amoebae in the lighted area will, in a short time, become restless and begin to move about and will finally move away from the area of light. By a specially arranged hot stage, so that there are areas of different temperature, amoebae will be observed to ac- cumulate in the areas of favorable temperature and emigrate from those of unfavorable temperature. That is, they respond to or are responsive to thermic stimuli. In a similar way amoebae respond to various chemical stimuli. If a drop of acid be so placed that it will slowly diffuse into the water or fluid in which the amoebae are being studied, they will move away from the acid. If an amoeba be divided by mechanical means so that one segment contains the entire nucleus and the other segment has no nucleus, it will be observed that the nucleated segment responds to the stimulus by regenerating tissus to re- place the nonnucleated segment which was removed. On the other hand, the nonnucleated segment of the amoeba may survive the shock of separation, but soon begins to degenerate and finally dies. Thus is shown the response of living struc- ture to photic, thermic, chemic and mechanic stimuli. If more complex animals be considered there will be ob- served a similar response to stimuli. Thus, the hydra responds to the various kinds of stimuli and has a remarkable power of regeneration of tissues. Vermes are very responsive to stimuli and all observers have noticed that when an angle-worm is cut in two both ends will crawl away. Vermes are among the lowest forms of animals that possess cells corresponding to white corpuscles or leucocytes of higher animals. These cells are observed to emigrate to the point of injury or to surround INFLAMMATION. 141 the foreign bodies or substances that are experimentally in- troduced into the bodies of vermes. This reaction is analogous to the reaction of the mammalian leucocytes. The discussion so far, has been with reference to animals that possess no blood or vascular systems, or at least only ip a rudimentary form. Vertebrates are more highly organized and are consequently more responsive to stimuli than invertebrates. Mammalia are the most complex in structure of all animals and they are like- wise most responsive to stimuli. : The mammalian cornea is a nonvascular structure being composed of fused layers of fibres arranged parallel to the sur- face. Between the layers of fibres connective tissue cells and lymph spaces are found but no nerves. The cornea is covered externally by the conjunctiva. If the cornea be irritated there will be a reaction, the extent of which depends upon the in- tensity of the irritant. A puncture of the cornea with a sterile needle produces the following reaction or tissue changes; (a) within a few hours after the injury the affected area appears swollen and the cells that were punctured begin to degenerate while the uninjured cells immediately surrounding the needle puncture become tumefied and vacuolated; (b) from twenty to thirty hours after the puncture, wandering cells appear in and around the injured area, and as the cornea is nonvascular they must be migratory connective tissue cells; (c) by the third or fourth day the punctured cells will have been removed. by solution or otherwise, from the affected areas. Those cells sur- rounding the injury will have divided by mitosis, the newly formed cells replacing those that were destroyed and_ the wandering cells will have migrated from the injured focus. (The destroyed epithelial cells of the conjunctiva are replaced by those next to the injury). If sterile iron dust, or other insoluble granular material is aseptically introduced into the cornea, a reaction, as described above, will take place, and, in addition, the migratory connec- tive tissue cells will ingest or incorporate the introduced par- ticles and carry them out of the injured focus. When the cornea is injured more severely, as by the ap- plication of a caustic solution (irritant), in addition to the above reaction, a migration of leucocytes from the marginal corneal vessels usually occurs within thirty hours. Some of the invading leucocytes become destroyed and some of them may multiply, but they usually all disappear from the point of injury within from forty to fifty hours. The length of time 142 VETERINARY PATHOLOGY, necessary for repair of such an injury is variable according to the extent of the injury and the readiness of response of the tissue. In vascular tissue the following reaction occurs. An asep- tic cutaneous incision unites almost immediately if the wound margins are placed and maintained in exact apposition. The tumefaction is slight because of the limited extravasate from the severed vessels. There is a slight exudate which coagu- lates and cements the margins or lips of the wound. In a microscopic section through such a wound some cells are found destroyed and others injured. The cells bordering such an in- jury sometimes increase in size to such an extent that they project into the cement between the two incised surfaces. Wan- dering cells and leucocytes in varying numbers appear through- out the entire injured area. The cement (exudate) and the de- generated and necrotic marginal cells are later absorbed. The cells bordering the incision multiply by direct cell division, the newly formed cells replacing those destroyed. New capillaries extend through the newly formed tissue. Finally the leucocytes emigrate and disappear from the injured area. In a more extensive injury, such as a gaping wound that later becomes infected, a more complex reaction is observed. The following changes take place during the first twenty-four hours after an injury of this nature is inflicted. There is hem- orrhage, the extent of which depends upon the size of the ves- sels severed and the gaping of the wound. The extravasated blood accumulates in the wound and also infiltrates the ad- jacent tissues. The injury (irritation) causes hyperemia, es- pecially of the arterioles, resulting in engorgement of the capil- laries. From the engorged and dilated capillaries there is marked exudation. The exudate escapes upon the wound sur- face and infiltrates the tissues of the injured area. The ac- cumulation of the hemorrhagic extravasate and the inflam- matory exudate plus the increased size of the vessels (hyper- emia) tumefies or swells the injured area. There is an ac: cumulation of mononuclear leucocytes or wandering connec- tive tissue cells in the injured tissue and an immigration of polymorphonuclear leucocytes. Many cells are destroyed out- right by the injury or by the action of infectious bacteria. Those cells bordering the destroyed cells are injured and be- come tumefied and may later undergo necrosis. The cells, es- pecially the connective tissue cells located peripherally to the injured cells, become enlarged and multiply by indirect cell di- vision. The injured cells are repaired and the newly formed INFLAMMATION. 143 cells are massed together and project outward thus replacing the destroyed cells. The discharge from such a wound after twenty hours con- sists of serum, shreds and fragments of necrotic tissue, dead cells (especially leucocytes) and a variety of microorganisms. The reaction in the above case consists of circulatory dis- turbances, degeneration, necrosis, and regeneration of tissues. Etiology.—The exciting causes of inflammation may act from within the body, hematogenous or lymphogenous, or from without, i. e., extraneous as burning, etc. They may produce their action by direct contact upon surfaces of the body as from a blistering agent externally applied, or, by contact internally, as from arsenic. They may produce their effect while being ex- creted, as in the production of nephritis by cantharides or tur- pentine. Some harmless agents may become irritants as the result of chemic change produced by some of the body juices or fluids (lysins). The causes of inflammation may be divided into two gen- eral classes, non-infectious and infectious. Non-INFECTIOUS.—The non-infectious causative factors are not as active in producing inflammatory disturbances as the in- fectious agencies, but they are of some importance and should not be overlooked. Some have positively stated that “There is no inflammation without infection.” Reasonable interpreta- tions of clinical and experimental observations supply sufh- cient evidence that there is inflammation without infection. The following are the principal non-infectious causes of in- flammation. Mechanic or traumatic—Surgical wounds which heal by primary union are undisputed examples of mechanically pro- duced inflammation. The reaction taking place in an aseptic incision consists in cell-destruction, slight circulatory disturb- ances, leucocytic immigration and regeneration of tissue. Such a reaction is typical of inflammation and the affected area is devoid of any infection. A sterile needle introduced into a tissue, the surface of which is aseptic, produces a reaction identical to the reaction observed in primary union of tissue. Mechanic or traumatic causes of inflammation may produce, or cause to be produced in the injured cells, chemic substances that are responsible for the reaction. Thermic-—A temporary exposure to a high or low tem- perature is sufficiently irritating to produce a marked inflam- mation. Let those doubting this statement take the chimney from a lighted lamp and hold it in the hand for one minute and 144 VETERINARY PATIIOLOGY. they will acknowledge that heat produces all the symptomatic evidences of inflammation and there is no infection. The prin- ciple object in the use of the thermo-cautery is to produce or estabiish inflammation. A thermo-cautery, or any severe burn, produces tissue necrosis, as well as the destruction of bacteria in that area (sterilization), and an inflammatory zone is im- mediately established around the necrotic tissue which is sterile and may remain free from infection. A short exposure to an extremely low temperature produces an inflammation. If the exposure is of long duration necrosis is likely to oceur. “Chilblains’ is an inflammation resulting from temporary exposure to a low temperature. Sloughing following freezing of calves’ ears, pigs’ tails and cocks’ combs are familiar examples of necrosis resulting from long exposure to extremely low temperature. An inflammatory zone is es- tablished around necrotic areas produced by freezing similar to the inflammatory zone observed around necrotic areas pro- duced by burning. Thermic variations may produce chemic substances in injured tissues which are sufficiently irritating to establish inflammation, Electric—Ilt is common knowledge that electricity causes inflammation. Animals injured by lightning usually show evi- dences of cutaneous inflammation. In cities animals as well as men frequently contact wires charged with powerful electric currents and receive local injuries that are usually inflammatory in their nature. Chemic.—There are maay chemicals that are irritants. A number of them are used as therapeutic agents when irritants are indicated. Muneral acids, caustic alkalies, mercury salts and arsenic are some examples of chemic agents that produce inflammation when applied in dilute solutions, and necrosis when applied in more concentrated form. A 10 per cent solu- tion of nitric acid applied to the skin for a very short time pro- duces infammation. Inflammatory symptoms following the nitric acid application appear immediately ; and, as the acid is a disinfectant, the inflammation cannot be the result of infec- tion. In animals poisoned by any of the mineral poisons there may alwavs be observed an inflammation in the mucosa of the alimentary tract more extensive than could have been produced by infection in the limited time of action. Many reptiles, bees, wasps, and ants introduce chemic sub- stances into animal tissues that are extremely injurious and es- tablish inflammation of very rapid evolution. INFECTIOUS OR VITAL AGENCIES are the most important etiologic INFLAMMATION. 145 factors in the production of inflammation because they are the most frequent offenders. Infection usually produce intlam- matory disturbances through the action of chemic substances elaborated by the infecting micro-organisms, as metabolic pro- ducts. The infection may be local and produce localized in- flammation as in a superficial abscess and in coccidiosis. The elaborated chemic substances may be absorbed from the local- ized infection and produce inflammation elsewhere in the body Infection may be general and produce conditions similar to in- flammation in practically all the tissues of the body as in gen- eralized anthrax. However, the term inflammation is usually confined to local disturbances. The extent of irritation pro- duced by any infecting organism is dependent upon the virul- ency of the given organism and the resistance of the infected animal. ‘hue, infection with Streptococcus pyogenes equi may produce pyemia in one animal and only a local abscess in an- other. Again, some bacteria, as the anthrax bacilli, may pro- duce septicaemia in one animal and localized inflammation in another. ing microorganisms and other foreign particles. Polymorpho- nuclear leucocytes having neutrophile granules are the most ac- tive cells concerned in phagocytosis. Endothelial cells and wan- dering connective tissue cells may be under some conditions phagocytic. The phagocytic property of cells is variable depending upon the virulency of the micro-organisms or strength of the chemic substance and upon the resistance of the phagocyte. Bac- teria are enveloped by protoplasmic extensions from the cell body until they are entirely included in the aggressive phago- cyte. After the enveloping process there may be observed diges- tion vacuoles surrounding the bacteria. The included bacteria are destroyed by ferments produced by the phagocyte. It is an intracellular digestion. The length of time necessary for the phagocyte to destroy the bacteria is variable. The bacterial destruction may be instantaneous or the bacteria may possess sufficient vitality to destroy the phagocyte. There is consider- able evidence that infection is frequently generalized in the ani- mal body by leucocytes that have enveloped bacteria and wan- dered to another portion of the body. The included bacteria destroy the leucocyte and, thus liberated, establish a new cen- ter of infection. Phagocytosis is a very important factor in inflammation. No doubt many localized inflammatory conditions are aborted and the intensity of the attack of other infective inflamma- tory conditions reduced by the process of phagocytosis. There is a peculiar variation of phagocytosis occasionally observed, 160 VETERINARY PATHOLOGY e. g., leucocytes becoming phagocytic toward other leucocytes. Fixed tissue cells may under some conditions become phago- cytic towards leucocytes; this perhaps is for the purpose of obtaining nutrition for the fixed tissue cells. The Signs of Inflammation.—Inflammation may be recognized in exposed tissues by the so-called “Cardinal signs: redness, swelling, increased temperature, pain and impaired function. These signs are usually perceptible in the early stages of acute inflammation, but they may not be evident throughout the entire process. Mild, chronic inflammation may not be accompanied by any of the above signs. These signs are very variable in either acute or chronic inflammation of internal organs. ee \ OG: Og 6 BE iE es! PGR on” a Fig. %S.—Acute Myositis, a Leucocytis exudate Muscle fibres disintegrated and vessels engorged. kedness (Rubor) is a constant sign in the early stages of acute inflammation. It is the result of an excessive amount of blood in the vessels of the affected area. Siselling (Tumor) is characteristic of acute inflammation. It is the result of the accumulation and retention of the inflam- matory exudate plus the increased amount of blood in the part. The extent of the sw elling is in a direct ratio to the density of the tissue. Thus the swelling resulting from subperiosteal in- flammation may not be detected because of its limited extent. On the other hand, the swelling succeeding inflammation of loose areolar tissue may be very extensive, as in cellulitis. The swelling resulting from inflammation is usually firm, dense and quite resistant in contradistinction to swelling resulting from INFLAMMATION, 161 oedema, e. g., the tumefaction accompanyi ng tendonitis is dense, while the swelling accompanying “stocking” is soft and doughy. The te miperature (Calor) of tissue affected with active in- flammation is ee increased. This is the result of the excessive cellular action in the inflamed area and the increased amount of blood flowing into the part. Pain (Dolor) is a common symptom cf inflammation, This may be re result of pressure upon nerve endings by the accu- mulated exudate. However, oedema is accompanied by an ex- cessive accumulation of fluid in the tissues, and oedematous tissues are not hypersensitive. It seems more probable that in- flammatory pain is the result of the injurious action of the irritant or soluble products of the exudate upon the sensory nerve endings. The inflammatory pain is often referred to some other part of the body, e. g., in pleurisy the pain frequently appears abdominal. Impaired function (Functio laeso) is a constant feature ob- served in inflammation. In the beginning of the process the function of the affected tissues (especially secretory) is in ex- cess of the normal, but this is succeeded in the later stages by depression of the function. The increased function is a result of increased nourishment, increased stimulation, and probably increased pressure is also a factor; the depressed or diminished function is the result of the injurious action of katabolic prod- ucts, produced by excessive cellular action, and of the irritant producing the inflammatory process. Thus, in the beginning of acute nephritis there is an excessive amount of fluid (urine) excreted. this is succeeded by diminution or complete suppres- sion of the excretion (urine). Effects upon the Tissue Involved. — As a_ result of the inflammatory process the tissues involved) may un- dergo various changes. These changes may be degenerative necrotic, regenerative or proliferative in character. Degenera- tion usually precedes regeneration, but the two conditions may be independent of each other; thus in ulceration, degeneration and necrosis may alone be evident, and in the formation of a tubercle of tuberculosis proliferation is the principal process. Both conditions may exist at the same time in different parts of an affected area, degeneration taking place in the center of the diseased area and regeneration or proliferation in the peri- phery. Inflammation not accompanied by either degeneration or regeneration is rare. The injuries or irritants establishing inflammation may and frequently do produce death of some of the tissue cells; necrotic tissue is sufficiently irritating to pro- 162 VETERINARY PATHOLOGY. duce inflammation, and necrotic areas are usually surrounded by an inflammatory zone. Inflammation is confined to the reactive process of the injured cells and should not be confused with the death of the cells or necrosis. Degeneration and regeneration are distinctly opposite pro- cesses. The former is destructive, resulting in impairment and death, while the latter is constructive, resulting in overgrowth and proliferation. Degeneration is caused by insufficient food, inhibition of irritating products, or excessive and frequently perverted functional activity. Regeneration occurs when there is an adequate supply of nutrition, and depends upon the rever- Fig. 99.—Chronie Pneumonia. a. (Leiomyoma 6... eee ere e eee eee , Sara: 4 Muscular-myoma DE Mlogiganin auty sree y eennalectcas z ' {Lymphangioma ..--- 2.2.0... eee Jeseular-angioma 4 77 me Vescular-angioma Cena te oo a pereuneae a. | Nervous-neuroma Round Cell -> { Spindle Cell { ~ L Connective-Sarcoma Myeloid Cell | Endothelioma | Placentoma Carcinoma ...-+---:- Hypernephroma Epithelium } Adenoma «--+++++++: Epithelioma ..-..---+ J Embryonic Tissue / ewoeI9L bho NI w~ VETERINARY F.THOLOGY EFILGROMA. Fibromata are tumors composed of adult fibrous connective tissue. They occur in all animals. The skin and subcutaneous areolar tissue is their most frequent location, but no tissue 1s exempt. They are frequently found in the region of the sternum of the horse and ox, in the ovary and uterus of the cow, and in the perineal and elbow regions of the dog. In the skin and sub- cutaneous tissue they usually appear as loose, circumscribed, nodular growths. Some fibromata have no well defined border or line of demarcation but are apparently diffused through the tissue. This type, however, is somewhat rare, and possibly they are not fibromata. They may become so large that their pres- sure produces atrophy, degeneration or necrosis of the skin cov- ering them, or the surface epithelium may produce sufficient new tissue to compensate for the increased surface. These tu- mors are usually single. that is, only one tumor occuring in the individual; but they may be multiple. Multiple fibromatosis is occasionally observed in the subcutaneous tissue of horses. They are variable in size, being so small in many instances that they are not observed in an ordinary examination. © \t i 8i~ eee . \ 78 CM aay tye eg eee s Lah e fe ae a Be o Be? ° ap eee eee on ts PON a: Mee « $8. pe ee -. uit, oe se Oo id eee el yet oy of See \s ate oe ° ae te) 40, On ° dae See Nias mts creas! ) Cr O 8 | Pate Df ,eeF \ “eee mes 28 : i o's eo sea eee et oS VamwaNe Fig. 175.—Section of Maxillary Carcinoma of a horse, showing the nesv of epithelial cclls surrounded by a stroma, appropriated from the pre-existing tissue and therefore is vari- able in quantity and structure. In some cases sarcomatous tissue constitutes the stroma. The stroma forms alveoli in which the carcinoma cells occur. In fact, the alveoli are, in many instances, simply dilated lymphatic spaces which have been invaded by carcinoma cells. Lymph is usually quite abundant and bathes the nests of the carcinoma cells in the alveoli. Because of the freedom of anastomosis of lymph spaces and the constant flow of lymph, carcinoma cells are easily and rapidly diffused. Karyo- kinetic figures are of common occurrence in rapidly growing carcinomata. There is usually an inflammatory reaction accom- TUMORS. 323 panied by a leucocytic infiltration in the adjacent tissue. In rap- idly growing carcinomata the cells frequently completely ob- struct the flow of lymph through the alveoli, resulting in degen- eration or necrosis. Mucoid degeneration is perhaps the most frequent variety, thus producing a mucous mass. Clinically, these tumors are malign. They are not circum- scribed, hence their extirpation is practically impossible. In fact, surgical interference usually stimulates them to more rapid de- velopment, and, in addition, opens an avenue for infection. They zi I ‘l Wf Ya Yj / “ [St |, a, Fib. 176.—Section of an Epithelioma of the hock of a hors: yas the sequel of an injury. Note the ingrowth of the columns of epithelial cells. form metastases. The metastatic tumors usually occur in the first lymphatic gland that the lymph passes through from the area affected with the carcinoma, Then by metastasis they will be extended on to the next group of glands and finally reach the blood stream and form carcinomatous emboli in the lungs, liver, etc. These tumors should be differentiated from alveolar sareo- mata, endotheliomata and papillomata. The sarcoma has a much larger nucleus in proportion to the size of the cell and the cells are usually smaller than carcinoma cells. In a cross-section of a Sok VETERINARY PATIGOLOGY. papilla from a papilloma the cells will be found arranged around the stroma instead of in nests as in carcinoma. Carcinomata are sometimes associated with other tumors as fibromata and chondromata, but they are more frequently in combination with sarcomata, in which the sarcomatous tissue forms the stroma of the carcinoma. The sarcoma cells are usually of the spindle-celled variety. Epithelioma.—This type is the result of an ingrowth of epi- thelium into the underlying structures and has been classed by some as a sub-variety of carcinomata. In this variety of tumors OIE, “Oa eo: et 3 ‘oy +, en! a rat heig ses iss eee X o Ay a fo : anit SOR UP eu. OS ots Cig 177.—KEnithelicma trom cye of an ox, there is considerable evidence that they are secondary to surface injuries. A horse with a large fungoid growth beneath the left eye was sent toa Kansas City veterinarian for treatment. The history of the case brought out the fact that the tumor was the sequel of a wire cut. Two similar cases of epitheliomata oc- curred in the eye of two cows after severe attacks of keratitis. Epitheliomata are not rare and may affect any of the domestic animals. They always occur primarily in relation to epithelial surfaces. The surface is usually denuded and there is usually an acrid, fetid discharge. They may appear as elevated nodular TUMORS. B76 masses Or as ulcerated surfaces and are rarely encapsulated. Their consistency varies with the amount of connective tissue stroma present. Their color is usually white or gray, although it may be quite variable as a result of degeneration or neerodis: The quantity of blood depends upon the vascularity of the tissue invaded. Microscopic sections of epitheliomata are usually very similar to carcinomatous sections, indeed, it is sometimes impossible to differentiate them from carcinomata. In the beginning of the tumor formation, if sections are made perpendicular to the sur- Fig. 178.—Section of a pearl cell Epitheltoma of the Subeutum of a li-year-old dog, showing pearl] cells and columns of epithelial cells. face, the ingrowing epithelium will be observed as columns of cells. These cell columns extend into the areolar lymph spaces and are then distributed the same as in carcinomata, the pre- existing tissue stroma becoming the stroma of the tumor. The presence of the epithelial cells or their katabolic products some- times produces a chronic inflammation of the stroma. The pres- sure produced from the thickened stroma upon the columns of epithelial cells may result in the formation of “pearls.” Epithe- liomata containing the “pearls” are designated pearl-cell epithe- liomata. 326 VETERINARY PATILOLOGY. Clinically these tumors are not as malignant as carcinomata proper, and they have less tendency to form metastases. They are frequently completely destroyed by surgical interference. Adenoma.—This is a glandular tumor. While it is similar toa gland it is functionless or has a perverted function. Though occurring more frequently in glands, as the kidney, mammae, mu- cous or sebaceous glands, testicle, liver, etc., they may occur in any tissue. Swine and dogs are most frequently affected with them. They are usually circumscribed, rather firm, nodular, white or grayish-white masses, varying in size from a pea to a Fig, 179 —VPhotugraph showing Mammary Adenoma of a bitch. man’s head. In section the gross specimen usually appears lobu- lated, and, if the tumor is large, there are usually necrotic centres here and there through it. The blood supply is limited, the ves- sels usually being obstructed by the pressure of the new-formed adenomatous tissue. In microscopic sections glandular cells are found in various arrangements as tubules, acini, etc. The mimicry, however, is not complete, and there is usually little difficulty in differentiat- ing adenomata from normal gland tissue. The cells vary in shape from short cubical to tall columnar. They are usually TUMORS. 327 arranged in a single layer, although the tubules or acini may be entirely filled with cells arranged layer upon layer. The type of cells adheres to the description given in discussing carcinoma. The stroma is usually composed of fibrous connective tissue and is variable in amount. Blood vessels are found within the stroma. The cells lining the acini may be active and the secre- tion is frequently retained, thus resulting in a cyst-adenoma. The accumulated secretion may cause degeneration of the stroma and the acini rupturing one into another produce a large cyst. Fig. 180.—Section of an Adenoma from the frontal sinus of a mule, showing the arrangement of tumor tissue into acini and tubules. Clinically these tumors, as a class, are malignant, but do not produce fatal results as rapidly as carcinomata. Many individ- ual adenomata are benign. A horse’s tail was recently ampu- tated that for three years had been affected with an adenoma of the sebaceous glands.