MVSCVM rnRMFUVCTUBRARY Cornell University Library SF 959.A2S36 A preliminary report on the Investigatio 3 1924 000 250 021 Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924000250021 A PRELIMINARY REPORT ON THE Investigation into Equine Abortion EXISTING IN THE PROVINCE OF ONTARIO BY F<' W. SCHOFIELD, D.V.Sc. Department of Bacteriology, Ontario Veterinary College, Toronto , (PRINTED BY AUTHORITY OF THE MINISTER OF AGRICULTURE) ONTARIO TORONTO : Printed by L. K. CAMERON , Printer to the King's Most Excellent Majesty 1915 A ^ 536 Laboratories, No. 5 Queen's Park, Toronto, January 33rd, 1915. Sir:— I have the honour to submit herewith some preliminary studies into Contagious Equine Abortion. The subject is one of great interest and importance to all engaged in agricul- ture, and of vital interest to the horse-breeders of the Province. TJntil the nature of the disease is clearly understood the drafting of eflBcient prophylactic measures will foe impossible. From these researches we have obtained much valuable information which should be of immediate use to those who have to cope witii this disease. I wish to express n\y gratitude to Dr. Amyot, Director of the Provincial Board of Health Laboratory, who in every way facilitated the work, and to Dr. Hunter, who has assisted so faithfully throughout the investigation. All of which is respectfully submitted. FRANK W. SOHOFfFLD. The Hon. Jas. S. D0ff, Minister of Agriculture, Parliament Buildings, Toronto. A PRELIMINARY REPORT ON THE INVESTIGATION INTO EQUINE ABORTION EXISTING IN THE PROVINCE OF ONTARIO The objects of this investigation were to determine the following important questions. First. Was the abortion occurring amongst the mares in certain parts of the Province true contagious abortion, the result of an infection with a specific organism? Second. If -contagious abortion what were the factors involved in the spread- ing of it from one district to another? Third. How can the disease once established be controlled and finally eradicated ? As many tests are now available for use in the diagnosis of disease the first question was answered in the most convincing "way without much- difficulty. The other two important problems are far from being definitely solved, but I believe that sufficient evidence has been obtained to be of material value in controlling thifs disease. Before entering into a detailed discussion of the work a brief description of the disease may be of value to the reader unfamiliar with contagious abortion. Abortion: Contagious and Spoeadic. — ^By abortion is meant the pre-, mature expulsion from the uterus of the foetus and its membranes. Colts horn before their time 'but viable are considered as premature births. Abortion not In~ frequently occurs among all domestic animals. However, it is very imfmrtant to remember that in both the Equine and Bovine species there are two distinct types of abortion, one contagious and due to a specific organism differing with the animal species, the other non-contagious and resulting from various non-specific causes such as ergotism, injury and during the course of some infectious diseases; in fact anything that profoundly disturbs the system. The non-transmissible type of abortion is of little significance in comparison to the contagious variety considered- in this investigation. Symptoms of Contagious Abortion. — These in many cases are entirely lack- ing. Generally speaking the more advanced the pregnancy the more pronounced are the symptons both brfore and after abortion. The prodromal symptoms unfortun- ately rarely are specific; eolicy pains, restlessness and occasional straining may be noticed. These in a pregnant mare should always be regarded with suspicion. The vulva is frequently swollen and a mucus discharge present. Immediately prior t» the aot of abortion all symptoms become more evident. The discharge which follows is generally very t5rpical, being chocolate-brown in color, fairly fluid, containing numerous small flaky particles. The odor is also very typical and offensive. The foetal membranes are unfortunately inclined to remain intact, which may necessitate their artificial removal. Common sequelae are metritis and leucorrhoea. The mortality is not high, but the animals affected frequently lose in flesh and hecome unthrifty. The foetus, if alive when aiborted, does not as a rule live long; those surviving undoul)tedly have an inherent tendency to septic arthritis. The appearance of an aborted foetus externally is normal, but on, post mortem examination evidences of inflammation and other changes in various internal organs, such as the spleen, liver, lungs, and testicles in a male animal, are revealed. The lymphatic glands throughout are frequently ehlarged and inflamed. A Brief 'Historical Sketch. — The earliest appearance of the disease on this {continent was in 1886, when it became for a time a serious menace to the horse- breeding industry of the Mississippi valley. The first endeavor to determine the. icause of the disease was made by Theobald Smith,* who jrablished in 1893 the results of his investigation into an outbreak occurring in Pennslyvania. It is most likely that the organism isolated by him at that time was the one since demonstrated to be the cause of contagious equine aibbrtion. From that date until the present time many continental workers notably deJong, Dassonville, and Eivieref have isolated -organisms, which seem to be very closely related to the one described by Smith, and with these organisms in certain cases have successfully produced abortion in pregnant mares. The most complete work in regard to the etiology of the disease has been accomplished quite recently by two American bacteriologists, GoodJ and Meyers§ both working independently, but i^ndoubtedly isolating the same organism and obtaining very similar results. Their investigations into the etiology of the ;disease were more complete than our own, but their conclusions in regard to mode of transmission are based on rather meagre data, while ours have a much stronger basis as will be observed in the discussion on the question. ! As to the occurrence of the disease in the Dominion of Canada no reliable information has been obtained. The first outbreak of the disease brought to my notice occurred in the spring of 1913. Later I learned that the disease had occur- •ed during the spring of 1912. During the fall of 1913 and the spring of 1914 ';ases were reported from the previous localities, and also from certain hithet'td' Uninfected districts. Veterinary surgeons and stock breeders residing in these listricts state that the disease was never known previous to the present outbreaks. With this brief survey of the disease I will proceed to describe the work rc- ■^ently undertaken and endeavor to answer the questions previously enumerated. Does Contagious Equine Abortion Exist in the Province? — The very fact that numbers of mares had aborted in certain localities made one strongly suspicious that a specific infection was responsible. It must not be forgotten that ilbortion may 'be concomitant with certain infectious diseases ; this is nOta:bly the ?a8e in some outbreak? of influenza. Also the presence of ergot in the food may ioroduce similar results. Both of these conditions were looked for and found to be ibsent. To prove that the cases resulted from a specific infection was the task to be i^ccomplished. In solving 'this the following tests may be applied to cases under investigation : (1) The isolation of an organism from most eases of the disease, and by animal jxperiments proving its specificity for producing that disease. This may be applied if no organism has been previously described as the causative agent. (2) By demonstrating the presence of the recognized cause when such exists. * United States Bureau of Animal Industry, Bulletin No. 3, 1893. ■)• Revue g^nerale de Medeclne Veterlnalre, xxi., Nos. 245 and 246, 1913. t Kentucky Agricultural Experimental Station, No. 1G5, 1912. § Meyers, Journal of Medical Research, Vol. xxix., Dec, 1913. (3) By demonstrating the presence of specific reactionary bodies in the tissues or body' fluids of the infected animals. Some few months previous to this investigation Good and also Meyers had each discovered an organism which they believed to be the cause of contagious equine abortion. Undoubtedly the same organism had been discovered by both; and named the Bacillus Abortims Equimis by Good. A fact of considerable interest! is that previous to Good's publication I had isolated an organism that proved to be the bacillus abortivus equinus from the Joints and blood of foals suffering from septic arthritis. Only after Good's publication did I realize the possible etiological significance of this organism in contagious equine abortion. In most of our cases the opportunity for isolating the specific organism was, not allowed, as we rarely saw the mares until days or weeks subsequent to their, abortion. It 'will be noticed later in the report that when the opportunity was available the organism was recovered. Before commencing the investigation I had thoroughly tested the organism, isolated from the diseased colts with a known strain of the bacillus abortivus equinus obtained through the kindness of Prof. Good, and satisfied myself that the two were identical. Thus at the commencement we knew that the organism described by Gqod as the cause of contagious abortion had been isolated from .diseased foals ,born in a district where later cases of abortion occurred. Why should not the cause of. abortion in both Canadian and Ainerican mares be identical ? Believing this tc , ,be the case our first object was to isolate the bacillus abortivus equinus from case! of . albortion, or by satisfactory tests to demonstrate the presence of specific anti- bodies in the blood of mares that had aborted. : Isolation of the Bacillus Aboetivu.s Equinus. — As the investigation onlj started when the frequent abortions of fall and spring had aibated, the opportunit] for isolating the causative .organism correspoudingly diminished. Vaginal .swabj were taken in all cases of recent a,bortiou, aiwi cultured out on plaiii and gentiaii violet agar; also dextrose broth was inoculated, to which had been added the sam;, bacterial inhibitant. In both broth and agar the gentian-violet was used in thl strength of 1 in 50,000 to 1 in 100,000. This was found quite sufficient to cliec' the growth of most gram-positive organisms, while not preventing the growth o J the gram-negative bacillus abortivus equinus. Experiments were made usin, varipus strengths of malachite-green in agar, but the results were not as promisin,] as those obtained from gentian- violet which was adhered to throughout the invest] gation. The table given later shows that in only the most recent eases of abortioL the badlhis abortivus equinus was isolated by this means. The results of seruii .reactions will satisfy the possible criticism that perhaps the mares were neve spt!cifi,caUy infected. Failure to isolate this organism would tend to show that tl: infection rapidly clears up, but one must remember that a negative result from » vaginal swab would not necessarily mean a total absence of uterine infection. IJ* to the present time we have not had the opportunity to make a series of cultures i uniform intervals from the uterus after abortion. Alteration in the culture medii and methods of isolation might produce more satisfactory results. This poii; requires further investigation. As cases Nos. 50 and 56 were the only two recent cases that we had tlj! opportunity of, observing it will be of interest to briefly describe them. | Case No. 50. — This occurred in a five year old mare during her first pregnane' The mare had aborted twehty-four hours previous to my visit. She appeared vej ..depressed, was breathing rapidly, pulse 90, temperature 105 deg. P. Exploratic of the uterus revealed the cause for the high temperature and pulse rate, there being at least a quart of foetid brown fluid present, absorption from which wa-s causing the toxaemia. A sample of blood was taken from the jugular vein and dextrose broth inoculated. A tube of blood was taken for a complement fixation test, and also a swab from the uterine exudate. The blood culture on incubation remained sterile, and strangely both the fixation and agglutination tests were negative. Such reactions are interesting, but difficult to explain. It might be mentioned- here that the reaction had changed to a very pronounced positive in both tests made one month later. (See Case No. 81). From the uterine discharge the bacillus abortivus equinus was isolated. This organism predominated very markedly over the other organisms present, viz., colon, staphlococci, and streptococci. Cultures from the foetus were not to be obtained, as the same had been buried. Case No. 56. — This mare had carried her foetus full time, and was expected to foal in a day or two. The foal, although apparently normal when born, survived for only a few hours. Post-mortem examination showed the internal organs appar- ently nomial, with the exception of the spleen, which was enlarged, and the testicles, which were very much enlarged and haemorrhagic. The lymphatic glands were inflamed and enlarged. Cultures were made from all internal organs which later showed uniform infection with the bacillus abortivus equinus. From the stomach fi mixed culture was oibtained, while the small intestine, which was full of meconium, gave a pure culture. This may have been due to the inhibitive action of the bile. The dam seemed perfectly well, but from the uterus the typical chocolate colored fluid was being discharged. Prom this was recovered the bacillus abortivus equinus. Thus the bacillus abortivus equinus, the recognized cause (in the United States) of contagious equine abortion, has been recovered from the uterine discharge of two mares that had recently aborted. As these were the only two cases investigated immediately at the time of abortion the results are very satisfactory. The proof that the organisms isolated were the bacillus abortivus equinus were based on cultural characteristics and serum reactions. ( See article on " The Etiology of I'vemic .\)-tliritis in foals"' in the -Journal of Infectious Diseases, Vol. 15. ISTo. 3. Sept. 1914, pp. 409-416). Demonsteation of Contagious Equine Aboetion by means of Specific Seeum Eeactions. — ^With the results previously recorded one might consider the question as to w'hether the disease contagious equine abortion existed or not was satisfactorily answered, making further work unnecessary. Had the investigation now ceased the extent of the disease would not have been ascertained, and our knowledge limited to the results obtained in cases Xo. 50 and 56. By carrying the investigation into other districts we have, by the tests now to be described, clearly shown the cause to be the same in nearly all the cases investigated. Two fr>ts which from previous experiments were known to be satisfactory were decided upon, i.e., the complement-filtration and agglutination tests. Specificity in reaction is the criterion by which these, as well as other biological tests, stand or fall. That is, a positive reaction or one interpreted to "mean past or present infection must only result when the blood serum of the diseased animal is brought in contact with the causative organism. If the reaction as used in the test can be produced by the blood of h'ealthy animals or animals sufl'ering from other diseases it is at once shown to be non-specific and useless. Before attempting to understand the mechanism of any serum test, however simple, the following law should be carefully read : "When an animal or man is injected with a soluble protein the tissues react to the substance injected producing specific bodies (anti- bodies) which are capable of neutralizing the protein injected and are in excess of it." The dose must, of course, be non-lethal. Thus, when an animal becomes infected certq,in proteins are liberated in the tissue^- by the infecting organism. These stimulate the animal economy, which responds by producing specific counter-sub- stances (antibodies). All serum -tests depend upon the presence and identification of these specific antibodies. The following illustration will show what is meant by. specificity of reaction, and how it is utilized in the diagnosis of disease. An animal is thought to be infected with one of the two diseases- — tuberculosis or glanders. A sample of hlood is obtained, and the serum in suitable dilutions is added to a suspension of glanders bacilli in a test-tube. If no reaction occurs in the tube we presume that there was nothing present in the blood capable of reacting with the glanders organism and producing some change, such as precipitation of the suspended bacilli. We therefore presume the animal to be free from the disease glanders. At the same time the serum of a known glandered animal manipulated in a similar manner causes a pronounced precipitation of the suspension of glanders organisms. Blood serum derived from a known healthy animal and used simultaneously in a test gives a negative result, i.e., no change in the test-fluid. To test the blood of this same animal for tuberculosis, the tubercle bacilli are substituted for the glanders bacilli, and suitable dilutions of the blood seraiii made. This time the tubercle bacilli are thrown out of suspension, collecting at tttc bottom of the tube, i.e., a positive reaction, A control tube containing normal blooct serum is unaltered while a second control containing the serum of an animal known to be infected is similar in appearance to the suspect. Thus we see that the blobd serum of an animal infected with tuberculosis reacts only with the organism causing tuberculosis, or in other words reacts specifically. As a result of the infection with tubercle hacilli something has been developed in the animal economy that will react with the organism causing tuberculosis when given the opportunity. 'No reaction took place when the glanders ibaccilli were used, because the animal economy had never become infected with this disease. The reactions, whether occur- ring in the hody or in a test-tube are always specific. As will be seen later the agglutination test in unusually suitable for the diagnosis of the disease, and a few words describing the test will make it intelligible to the lay reader. By agglutination is meant the clumping together of bodies, organic or inorganic, that previously had a discrete or separate arrangement. This phenomenon was discovered several years ago by Grubler and Widal. Their investigations showed that when an animal was experimentally or naturally in- fecfted wiili an organism "X" the blood serum of an animal so infected when added to the • infecting organism would produce a change in their previous arrangement, clumps bein'- formed by the eomins; together of isolated organisms. It must be mentioned that the concentrated or weakly diluted blood serum of most animals will cause a limited amount of agglutination with most of the bacilli, or rod-shaped organisms. This normal agglutination is avoided by using the serum in high enough dilution to oibviate such error. Briefly, the test was performed as follows: — ^Equal quantities (3 cc.) of a suspension of the- bacillus alortivios equinus in normal saline were placed in a number of test tubes. Then to each tube was added a definite small amount of the^blood serum of the animal suspected to be infected with the bacillus of con- tagious equine abortion. When properly done each tube would represent a different. ' dilution of the blood serum, usually from 1 in 40 to 1 in 1,000. The tubes were .then incubated at 37 degrees C. for three hours and. then placed in the ice-chest ■for another period of twelve hours when the results of the tests were determined. The blood serums from normal mares were always tested at the same time for controls. Tru: Complement-fixation Test.* — It is almost impossible to describe this test in a way that can be readily grasped by one unfamiliar with serological diag- nosis, without entering into a wearying amount of detail. The test is based on the principle that when the fresh Ijlood serum of an immunized or naturally in- fected animaljs brought in contact either in vitro or in vivo'with the immunizing body, a reaction occurs between the two into which that constituent of the blood scrum known a,s complement enters and is fixed. The test consists of two parts. In the first complement is giv.en the opportunity to beeome fixed; the second part of the test is to demonstrate whether or not the fixation of complement occurred. This test to be of any value must be specific, that is, when a reaction is obtained indicating ihe presence of the disease in the blood of an animal under investigation, we must have enough confidence in the test to consider that the animal in question is, or has been, infected with this disease and no other. When properly manipu- lated the test has given eminently satisfactory results, and is considered the mo?t accurate serum reaction that can be used in the diagnosis of disease. To ensure specificit}^ of reaction suitable controls must always be employed. Our work, as will be seen by the tables, was carefully controlled by the use of normal horse serum whenever a test with suspecterl scrum was being made. Also two organisms, differing from the tested organism yet closely allied to it, were used in the test to fully prove that the reaction occurring was specific. As will be seen by studying the tables, fixation of complement only occurred with the hacillus abortivus equinns ■and not with an allied strain, viz., tlie bacillus coli communis. It is also interesting to note the absence of fixation with a closely related organism, the bacillus cholera ■suis. Further than this, the strains of the bacillus abortivus equinus received from Professor Good were used, and the results with these were the same as with our •own strain. Fixation of complement indicate^ that the blood came from an animal that ■was or had been infected with the organism with which fixation occurred. The samples of blood were oljtained l)y bleeding from the jugular vein with a large hypodermic needle and collecting in a sterile test-tube. Frequently some diplomacy had to be used before the farmer would allow such a harmless operation. The table which is appended contains, with the agglutination and fixation tests, the most important data obtained during the investigation. From this data the answers to the other important questions are derived. Many points of. interest are brought out in this table, but only those bearing directly upon the previous discussion will be mentioned here. First. — All the districts in which abortions have occurred and in which samples of blood have "been taken reveal the fact that the abortions in the majority of cas(>s were due to the bacillus abortivus equinus. Second.— ^Tha,t the agglutination and complement-fixation reactions parallel each other M-ith great accuracy. In almost all cases of fixation the agglutination titre is high and vice-versa. However, a combination of both should be employed to ensure greater accuracy. In most cases where the reaction failed to show up the abortion had occurred many weeks and occasionally months previously. *For technique of complement-fixation test, see Etiology of Pyaemlc Arthritis — Schofleld. Journal of Infectious Diseases, Vol. XV., pages 409-416. Oi Q 00 • a § ^ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 78 74 75 '76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 Owner. ]Jno. M . JEli R G. H. .. R. McA '. R. J. R. H. S.. C. K.. Jno. C. JA. J. H !a. T. ., iJos. B. Ira S. . Livery . H. B. C. B. R.N. E. B. H. H. C. L. C. G. L. D. R. T. C. S.. E. G.. Geo. D. Jno. D. Jno. T . W. M . B. C. . J. H. . . W. K W. T McC. '.'.'.'.'.'. H. T. H. R.... T .. Geo. D. H S.B.... F. D.... S.C.... W. H. D W. J. B. H. Description of Case. No. of Stallion J2 s Q o c r-. (O D,J4 a "S g > °JI1 if cs 3 & « Results of Agglutination Tests, dilutions made in normal saline. J_ 40 1 80 1 100 J. 200 1 300 1 400 1 500 750 Mare which had aborted Normal mares in same stable . Mare which had aborted O.K. Normal gelding mare . . , One year old Alley Mare which had aborted. Normal mare on same farm. Mare which had aborted Normal mare on same farm . Normal gelding Mare which had aborted Normal mare on same farm . Mare which had aborted Normal mare gelding 5 6 7 7 8 7 9 10 7 11 Apparently normal mare Mare which had aborted . 12 12 Stallion Mare had aborted 24 hours previously Mare had aborted Normal mare had joint ill foal Normal mare in same stable Mare that had aborted 13 14 15 16 12 15 15 15 15 16 15 17 May 5,1914.. Ap'l 30, " .. 12 38 75 30 May 11, 1914.. Ap'l 15, 1914. Feb. 15 " . 18 60 Feb. 15, 1914. "17 " . Mar. 7 " . ' ' 5 ■ ' . Feb. 1 " . Nov. 3,1913. Feb. 21, 1914. Ap'l. 4 " . ■• 17 " . Jan. 15 '' . 98 103 90 67 210 210 68 60 41 125 18 11 11 18 18 18 18 18 11 11 18 11 11 18 11 11 11 Negative Negative Negative Negative May 14, 1914.. Negative May 1, 1914. Ap'l. 13 ' ■ 4dys ov'rtime I 34 Ap'l. 24. 1914.. ' 8 ■' .. ■ 23 " .. Oct. 25, 1913.. Ap'l. 23, 1914.. • 17 " .. • 7 •' .. ' 21 '• .. 7 12 30 13 51 161 30 30 79 50 June 2 1914.. Negative 2 " ..! 2 ' ' "" 2 ' ' " 2 " .. 2 " + + + — + + + + + + + + 4- + -^ + + -t- + + + + + ' + + + — + + — + + — 4- + — — + + + + + + + + + + + + + + H- + + + + + + + 18 18 19 iMay 22, 1914 . lAp'l. 20 ■ ■ . 20 May 1914.. Mare had aborted 24 hours previously ' ' ' 24 ' ' . . Normal mare, in foal ; Second year she had aborted , Aborted one year ago (Jesse) (Lady) , ' Normal mare (Fly) j Mare that had aborted ' jJune 1, 1914. . 14 m 1 35- Mare that had aborted No . 5 No. 6. ... Normal mare, same farm, No. 7 . No. 8.. Normal mare , foal died , joint ill Normal mare had still born foal. . Mare that had aborted 21 June 29, 1914.. 30 32. 21 June July, 21 19 Ap'l. 15, 1914.. j Mar. 15 " .. 60 21 Normal mare, not pregnant. . . Mare that had aborted Normal mare , pregnant ' ' never pregnant . 22 19 ■Ap'l. 20 30 Mare that had aborted Normal mare not pregnant Mare that had aborted Ap'l. 30. 1914. Gelding in next stall. Normal mar 21 21 22 18 Ap'l. 17, 1914.. " 24 " .. IMar. 10 " .. [May 22 " . . e, colt died of joint ill 18 18 18 22 18 18 colt died of .joint ill 18 23 ,9 ^0 70 May July 24, 1914. 24 " . 25 " . 25 " . 24 " . 24 •■ . 25 " . 25 " . 25 " . 25 " . 25 " . 25 ■' . 15 " . 1914. Positive Positive. + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + + + + : + + + + -t — + + + — + + = Presence of good reaction. +—= Doubtful reaction. —= Absence of positive reaction. le Besnlts of Fixation Tests. J ^ ■? a Results of Agglutination Tests, dilutions made ^ in normal sahne. Antigens used. o > ■ i Remarks. ' as ^ s Bacillus Bacillus Bacillus B.Abortivs 3 & 1 1 1 1 1 1 1 1 1 Abortivus Cholera Coli Equinus ^"^ 40 80 100 200 300 400 500 750 1000 Equinus. Suis. Communis (Good) May 11, 1914.. Negative — — — — — — — — i 4- — Not done -, 4- S v V " 18 •' .. •• 11 ■' .. Negative + + 4- + 4- 4 + + — ' — — — T — — ' ' 4) . c"a '• 11 •■ .. " 18 •• .. — — — - — — — — + — — ts'is Uect sted come " 18 " .. •• 18 •• .. — z — z L_ — — — — — — ' ' ISh^ ■• 18 ■■ .. ■• 18 •• .. •■ 11 •• .. '• 11 ■■ .. — — — — — - ' — — — — — — " 4i M_, rj' -ia Negative — — — — — r — — — 4- 4- — i — ; '■ 18 ■■ .. k . . + + + — — ' — _ , , ^12'^ ■• 11 ■• .. Negative — — — , ' __ i , , ■• 11 •• .. ■• 18 •' .. " 11 ■■ .. " 11 ■• .. " 11 " .. ! + 4- 4 ^H 1 ^ — — 4- -i- — — ■ ■ irregular te dale of cted May 314. Maui ... — I — I — ! i 1 , May 11, 1914.. Negative + 4- 4- 4- 4- 4- 4- 4- — 1 1 + 1 1 Not done ' ' + 4- 4- 4- -r -^-^- -U -(- * ' ' ' ' ' . . ' * -f 4- + + 4- + + i- * ' * ' + 4- 4- 4- + + 4- 4- ' ' ' ' ' ' . . ' ' + 4- 4- 4- — 1 ' ' ' ' ' ' . . ' ' + 4- -r '4- — 4- 1 4- 1 ' ' + 4- 4- 4- — 1 1 ' ' ■ ' • + 4- 4- 4- — — 1 1 _ __ ' ' ' ' ■ ' . . ' * + 4- 4- 4- — + — — ' — — — — — 1 1 . . . . ^ ^ ' ' — 1 — — — . — — 1 — ' ' ' ' ' ' . , + ! 4- 4- 4- + i +--i - — 1 — — — — — — 1 — j — — j — 1 — — — — — — ~ i 1 — 1 "— i — " — — — ' * ime June '^ 1914.. Negative 4- 4- 4- 4-- 4- 4- — _ _ 4- ' ' - ' ' . . ' ' 4- 4- + 4- 4- f — — — 4- — — This m?re suffered from acute metritis. ' * / ' ' , , * * + 4- : 4- + 4- 1 + , — — — 4- . ' ' - ' ' . . ' ' + 4- 4- — — 4- ' ' 'J ' ' . . ' ' + 4- i 4- 4- 1 — i j — 4- + + 4- 4- V ' ' . . * ' + 4- 4- 4- 4- _ — 4- :: ^ :;:■ + + 4- 4- + 4 4- 4- 4- 4- 4- + + + 4- 4- + 4- 4- 4- + — — Ag-glutiaation 4- 1 4000 :: ■ '.: ■■ . « + + 4- 4- 4- 4- 4- 4- 4- 4- + + 4- 4- + — — Agglutination 4- to 1 2000 Agglutination 4- to 1 \\ r w ■■ J J + + 4- 4- 4- 4- + 4- -L 4- 4- + 4- — + ■. .. • ■ + — 3000 ' ' 1 ' ' . . ' ' — z — — — — — 4- — — -4- — — — — — + — — — — May 24, r._,!4.. " 24 •■ .. Positive. _ 4- 4- + 4- + 4- + — 4- — Same as No. 81. July 25 ' ■ + + 4- 4- + + + — 4- " 25 ■ ■ . . " 24 ■' .. + — — 4- 4- — E fn foal bul did,xiot become infected. Sample lost before Agg. test made. + — in 1 200( •• 24 " .. Positive. + 4- 4- 4- 4- 4- 4- 4- 4- 4- 4 — + 4- ' ' 95 ■ ' + 4- 4- + 4- 4- 4- + — — ... ' ' 'y>5 4- 4- 4- 1 " 25 " .. " 2'. • ■ . . + + 4- 4- 4- — — _ June 15 '' .. July, 25 1914.. ' ' 25 • ' + + -f 4- 4- 4- 4- 4- 4- + 1 [ 4- — 4- — — + 4- 4- 4- 4- + 4- + 4- 4- 4- 4- 4- + i + — 4- — = 1 These mares were in foal on same farm worked with No. 63 and 64. " 25 ■■ .. " 25 •■ ., lived and • . — " 25 •• .. + + 4- 4- 4- 4- 4- 4- 4- — 4- " 25 " .. + 4- 4- 4- 4- 4- 4- — — ^ — — " 25 " + 4- 4- 4- 4- 4- + — — 4- — — " 25 " .. " 25 ■' .. ■' 25 " .. " 25 '• .. + -l- 4- 4- + — — — — — — — c5 n3 " 25 " .. " 25 " .. " 25 " .. + + — — — 4- 4- + — — + — — a • » • 4- 4- 4- 4- 4- 4- 4- — 4- 4- — d " 2o " 4- 4- ■4- 4- 4- 4- 4- 4- 4- 4- 4- 4- — 4- — 4- — — CO " 25 '■ .. " 25 " .. " 25 '■ .. " 25 " .. '• 25 '■ .. " 25 ■' .. ■' 25 '• .. 4- 4- 4- 4- 4- 4- 4 4- — — 4- + 4- + 4- 4- 4- 4- 4- 4- — — 4 — — — — " 25 ■' .. " 25 " 4- — + — 4- — — — — •■ 25 " .. " 25 " .. " 25 " .. " 25 •' .. 4- 4- " + " V !_' 4- — = good reaction. 4-—= Doubtful reaction. —= Absence of positive reaction. rArrrf.— Omitting the eases in group " B " it will be noticed that betwreen 70 and 80 per cent, of the abortions occurred during the last month of pregnancy. Fourth. — Nos. 83, 53, 57, 33 and 92 are very interesting cases. These mares had not aborted and were apparently healthy, yet they gave positive fixation reactions. These cases will be discussed later on in the paper. Fif^h.— The cases in .group " C" seem to point directly to the influence of the sire, i.L'., seven of fifteen mares were bred to the same horse. Sixth. — As before nientioned the specificity of reaction is closely shown, no positive results being recorded when other organisms such as the colon bacillus or the bacillus cholera suis were changed for the hacillus abortivus equinus. The ' parallel reactions with Good's strain and my own, confirm previous work as to the similarity of these organisms. (See cases Nos. 33 to 49.) Seventh. — ^Antibodies may still be found in the blood-serum of a mare as late as seven months after the, abortion. (See case No. 25.) The first question aske^l in this investigation, i.e., whether contagious equine abortion exists in the Province, has been satisfactorily answered, also the relation- ship of the bacillus abortivus equimis and contagious equine abortion as existing in this Province established, WIT AT ABB THE FINDINGS INVOLVED IN THE SPEEAD OP THIS DISEASE FROM DISTRICT TO DIiSTRICT ? Unfortunately, at present, we have but meagre knowledge as to the way in- fection spreads. Investigators seem to have relied too much upon animal experi- ment to obtain such information, instead of making a thorough epidemiological in- vestigation, ("iood, in his article, does not tackle, this problem, discussing only the ' ciiuse of the 'disease. Meyers, while not making any definite statement as to the way of infection, believes there is an incubation period of about fifteen days between infection and abortion. This would practically eliminate the possibility of stallion infection. It is worthy of note, however, that the five naturally infected cases upon which his report is based occurred in mares all bred by the same stallion. I do not think that the experimental work of these authors, excellent as it is, warrants any con- clusion as to the mode of natural infection or length of incubation period. During the latter period of the investigation — notably cases 60 to 80 — a special attempt was made to collect all information that might throw light upon this phase of the problem now ))eing discussed. It must he remembered that con- tagious equine abortion was a new disease in the district where it occurred during the past two seasons. The epidemics, therefore, cannot be considered as sudden outbreaks of latent infection. We also know that diseases do not occur spontane- ously, but always have some specific organism or organisms as their cause. How the infection first entered the -Province will most likely never be known. That it did not occur years earlier as the result of frequent introduction of horses from the infected districts in Europe and the United States is at least surprising. The Important Question Now is, "How Does it Spread?" — Due to the fact that the investigation was not started until late this spring (May, 1914), an attempt .to follow the outbreak from town to town was impossible, although I thought that by careful investigation of individual cases just as valuable results 10 could be obtained. The following were some of the most important questions put to the owners of mares that had aborted: ' ' ^ 1. When did your mare abort? 2. When was she bred? 3. Do you remember any other mare bred at the same time? 4. Which mare aborted first (when more than one aborted) ? 5. Had there been any abortion previously on the farm? 6. Had any of your pregnant mares been on a farm where abortion had recently occurred, or had mares from a farm where abortion had occurred been stabled in your barn? 7. Had any food been purchased from a fp,rm where abortion had occurred ? The owners generally knew where the other abortions had occurred in the immediate districts, so there was usually no difficulty in determining whether their stock had come in contact with possible infectious material. A sample of blood would then be taken from the mares that had aborted and from the other normal animals. All these questions, and more, were asked with the one chief object, viz., to know how the disease was disseminated. Eemembering the two recognized portals of infection, the mouth and f.he vagina, let us see what local conditions are necessary before infection can occur through these channels. If infection is to take place through the mouth, then we must admit infection of the food. But how can this occur when in many of the cases, in fact almost all, the food had been grown and stored on the farm which previously had been ab.^olutely free from s^uch a disease. The water, likewise, in no way could have the primary source of infection. Even when due to food the contamination would have to be recent to be dangerous. When a mare has aborted on the premises the food is most likely to become infected ; but here it must be remembered that of thirty-five farms visited where abortion had occurred, on six- teen alone were there more than one case. In these, although possible, it is not likely that the infection spread from one to the other by the eating of contaminated food. y ' Infection by the vagina subsequent to conception can only occur by the preg- nant mare lying'on bedding that is heavily contaaninated with the bacillus dbortivua equinus. How is such infection possible, before at least on^ case has occurred,, on the farm? Infection by the mouth or vagina is highly improbable until the stable has become infected, due to a mare aborting. Secondary cases may arise in this way and most probably do, but primary cases occurring in previously uninfected districts cannot be accounted for in this manner. It is, however, a possibility that infection is spread through livery stables. Here the horses are all watered from the same trough or pail, and the hay left by one is eaten by the next. Against this source of infection lAay be mentioned : first, the disease should be fairly evenly distributed in the district around the town in which the livery stable is located. This was not the case. Secondly, that few cases occurred among the driving horses, yet these were the horses most frequently exposed to livery-stable infection. Third,, the organism responsible for the disease is not, as far as is known, present inthe mouth of the animal infected. The belief that infection occurs almost exclusively by way of the mouth or vagina subsequent to conception is probably due to the fact that most investigations have been made in connection with breeding establishments where many cases occurred in the same stable. TTnder such circumstances undoubtedly the possibility 11 of infection through these channels is greatly increased. If the above-mentioned are not the common portals of infection, then what are? Transmission by Coitus. — The previous modes of infection being considered untenable in these epidemics, some other method was" sought for. Viewing the situation in a casual way the untrained as well as the expert observer would con- sider the role of the stallion in spreading the disease of some imptfrtance. Here were stallions breeding mares that had aborted in the infected districts and then travelling around into uninfected districts, breeding as they went. Certainly some precautions were taken to prevent the stallion carrying infection such as pseudo- disinfection of the penis, and not breeding mares that had aborted until a period or two of oestrum had passed. Even such precautions as these were by no means always taken. Before considering this method seriously, i.e., infection being trans- mitted by the stallion from diseased to healthy mares at time of coitus, it is necessary to ascertain whether infection remains in the uterus of the mare for any length of time after abortion. This we attempted, but with little success, as indicated in the tables. This, I think, is due to the fact that specimens were taken too late after the abortion, and also vaginal sw^abs alone could be obtained. The swab should be taken during the period of oestrum, when a good chance is offered to determine whether infection exists in the uterus or not. Some data from Meyers' investigation will help to clear up the point. In five rases of natural infection in mares, the organism was recovered from the uterus in one case twenty- seven dayf, and in another twenty-four days after the abortion. In experimental infection induced in a goat, the organism was recovered seventy-five days after the abortion had occurred. He c'onsiders that failure to isolate it from the other three cases of natural infection was due to the use of antiseptic douches. The persistence of the organism in the uterus makes the animal a serious menace when careless methods of breeding are employed. Instead of considering infection by means of the stallion as outlined above, a mere possibility, I think it should be considered the most probable way in which the disease spreads. I wish now to bring before you a number of cases investigated strictly from the epidemiological standpoint, that is, in these cases our main object was to dis- cover the way in which the disease spread from animal to animal. To elicit the necessary answers from the owners the questions previously mentioned were used. The points of most importance in regard to the epidemic in District "C" may be summarized: 1. All the cases occurred within a period of three weeks, except No. 43. (The owner being absent accurate information could not be obtained in cases 35 to 39 inclnsive.) 2. Fifteen cases occurred on eleven different farms. 3. None of the farms on which abortion occurred were adjoining each other. There was at least one farm, and perhaps more, free from infection between those on which the abortions occurred. Thus an abortion on one farm eould ilot be considered as iniiuencing the abortions occurring on other farms in the vicinity. (The owners stated that their stock did not mix.) 4. These mares had all been served by stallions passing through a near by in- fected district. The facts of this outbreak make infection by mouth or vagina (subsequent to conception) in most of the eases impossible. Also there is no evidence of a fifteen-day incubation period. After a careful survey of the situation I am convinced that the common source of infection for the mares were the stallions to which they were bred. 13 These, after breeding to mares in a district where abortion was epidemic, were, ■ without satisfactory, precautions, used for service in District "C," which up 'to that time had been free from infection. If this was a very infectious disease, having a brief incubation period, there might be a possibility that case Ko. 46, occurring on April 7th, was the nucleus of infection for the subsequent cases. ^ Our present knowledge of this disease is, however, absolutely opposed to such- a suggestion. When several cases occur on the same farm, separated by a reasonable period of time, the latter cases may be, and most likely are, secondary cases arising from the primary one. The following table has been compiled from data previously recorded, with the object of studying collectively those cases in which more than one abortion- occurred on the same premises. Only cases where accurate information was obtained are included : — Case No. !f: III: (20. 121. (23. 122. I "{It 42. (69 )7I 70. Owner. Jno. M No. of Stallion. 1 1 .i 3 •1 ^ :! 6 7 .; 7 .' 8 ■1 7 .: 16 17 .! 22 G. H A. S C. C J. a... C. L T McC ' (U ' Wm. K 63 " .. Date Aborted. April- 30 5 Result of tests. I ixation. Agglutination. Feb. 15 April 15 Feb. 15 Feb. 17 March 5 March 7 Nov. Feb. + + April 8 April 23 May May ; 76a j H mare sold but aborted on ^70 j '• i April 15 March'15 June 29 ? farm in February April 30 + + + + + + + + + + 4- + + + In four of the ten cases, namely A, C, D and G, the incubation period is alto- gether too brief to consider that the infection of the second case was derived from the first. 'In the remaining few cases a reasonable incubation period exists. The important point is: from irhencv do the priinari/ cases arise? In almost ail cases the infected mares were on farms widely separated, and no mingling of stock had 0('curred. Most of the abortions were over before the animals had been turned out to pasture. In only one instance, case No. 72, was there a history of the mares previous to abortion being on infected premises. Again, I would state that tlie only possible source of infection open to all cases were the stallions that travelled from infected to uninfected districts. 13 The history of the following cases was recently received from Dr. Duthie, of Pincher Creek, Alberta. In the fall of 1912 seven, mares of his were bred to two stallions, X and Zriive to the former and two to the latter. All proved to be in foal. Of the five mares bred to X three aborted, one lost her colt during parturi- tion, while the foal of the last one developed septic arthritis, from which it finally recovered. The two mares bred to stallion Z delivered healthy foals. These seven mares were kept under similar "conditions. Stallion X travelled through the district breeding indiscriminately, and many mares served by him aborted. Stallion Z was the property of Dr. Duthie and had never been used for service before. Quot- ing from his letter, he says, "The loss appears to have been greatest in those herds where travelling stallions were used, and least where they bred only to their own." The argument always used against the idea of stallion infection, especially by those whose interests depend, upon the good reputation of the stallion, is that, if the stallion carried the infection, all or almost all mares bred to him would abort. The Statement demands too much. In no disease do all those exposed to infection become infected. Individual resistance, even among-st the same animal species and to the same disease, varies greatly. Also there is good reason to believe that' the infection is not a very virulent one and the following facts are in evidence of this. A mare may become infected with the bacillus abortivus equinus to an extent sufficient to produce a positive agglutination and complement-fixation reaction without showing any symptom of disease at all. The following examples illustrate this point : Case No. 52. — The bacillus aboriirvs equinus was isolated from the joint of a foal that was sufPering from septic arthritis. A sample of blood J;aken from the dam gave positive agglutination and fixation reactions. The dam always appeared to be perfectly healthy. One case of abortion had occurred on the farm. Case No. 57. — While- investigating case No. 56 a sample of blood was taken from a perfectly healthy mare on the same premises that was due to foal in a week or two. This sample gave a good fixation and agglutination reaction. The mare delivered an apparently healthy foal, but it was weak from the first and died in a few days. Case No. 83. — This mare delivered her colt a few days before time. Abortion not suspected. Colt developed septic arthritis and died. The bacillus abortivus equinus was isolated fom the cadaver in pure culture, while the mare's blood was tested and gave splendid fixation and agglutination reactions. The mare never showed signs of any disease. Case No. 91. — The mare had a colt M-hich developed septic arthritis and died. A blood sample of the mare showed positive agglutination and fixation reactions. The mare was never known to be unwell. Several other cases of this kind occurred last year (1913). In further support of the statements that the infection is not virulent in type or one that would be considered highly infectious is the fact that on many farms where abortion occurred mares carried their foals full time and never became in- fected, although standing in adjacent stalls to mares that had aborted. To make sure that such apparently healthy mares were not infected, fixation and agglutina- tion tests, were made on their blood, which in every case proved to be negative except in the one cited above, No. 57. In all diseases of the less malignant type there are a number of animals which seem to possess a natural immunity and thus escape an infection to which their species is vulnerable. I think that the, above argument with its evidence satis- . 14 fa(;torily explains why comparatively few mares in a district abort, even if the uterus is infected at the time of coitus. Before closing the present discussion I would like to draw particular attention to cases Nos. 52, 57, 68, 83, 33 and 92. These are most probably the really dan- gerous cases in spreading the disease, as the owners never suspected abortion and took no precaution with regard to quarantine or time of breeding. I would not wish those reading this section of the report dealing with the spread of the disease to consider my attitude as one of absolute hostility to the orthodox belief in infection by mouth or vagina (subsequent to cottGeption). My endeavor has been to show that these methods of infection will not explain all cases, and that infection occurring during coitus, having much evidence in its favor, should -be given more serious consideration. THE COISTTEOL OF CONTAGIOUS BQUIXE ABORTION. Even with our limited knowledge of this disease certain prophylactic measures suggest themselves, whidh, if systematically adopted, should be of considerable value. The following regulations should govern the breeding of mares that have aborted : 1. A period of three months must elapse between abortion and subsequent breeding. 2. Mares that have aborted must not be bred if there is any evidence of uterine catarrh, even rf the necessary three months have elapsed. « 3. Mares which have aborted must only be bred at the end of the stallion season. 4. That the application of an efficient disinfectant to the penis of the stallion be made compulsory aftei* each service in the districts in which abortion is prevalent. (Districts to be defined.) These regulations should' also extend to mares in infected districts whose colts have become infected and later developed septic arthritis. This would limit the number of very dangerous disseminators, a> I believe cases Nos. 52, 57, 68, 83, 33 and 92 to be. As will be remembered, these mares never aborted and were perfectly normal, yet they gave a positive reaction, indicating present or recent infection. The foals of all these mares finally snecumed to septic arthritis. Prophylactic Meastjees to be Employed at Time op, oe Subsequent TO, Aboetion : 1. At the first appearance of any symptom suggestive of approaching abortion, the mare should be isolated until the cause of her distress is known. 2. After abortion the foetus and membranes should be burned if possible, if not,, they should be buried deeply and covered with quick-lime before the dirt is replaced. The heavily contaminated foetus should never be dragged across the barn-yard or through the stable, but should be removed in a sack or wheel-barrow. 3. Those that handled the foetus or membranes, or in any other way became infected, should immediately wash their hands thoroughly and then immerse them in a strong antiseptic, such as 5 per cent, carbolic acid solution. 4. The bedding should be removed and burned. The sides of the stall should be washed with a strong disinfectant and chloride of lime freely sprinkled on the floor. 5. The vulva, thighs and tail of the mare should be washed with some good disinfectant daily. 6. Isolation should be maintained for at least one month after all-evidence of uterine discharge has ceased. The mare can then be removed and the stable thor- oughly cleaned and disinfected. 15 Dbugs in Prophylactic Tkeatment. — ^Carbolic acid, black haw and methy- lene blue are the most popular panacea fdrlDoth equine and bovine abortion. There is very little evidence to show that these drugs have any abortifacient action, and their use, at present, must be considered as empirical. Specific Prophylactic Treatment.— The use of vaccine made from the bacillus abortivus equinus (Good) after breeding might produce sufficient immu- nity to prevent the development of a recently planted infection. It is most unlikely that either a vaccine or serum, if such was produced, would be of any value after the infection has once beome established in the gravid uterus. Conclusions : 1. That the equine abortion occurring in certain counties of the Province is a contagious disease, and that it is identical with the contagious equine abortion existing in 'certain areas of the United States and Europe. 3. The organism responsible for the infection is the bacillus abortivus equinus {Qrooi). This organism has been isolated from the uterus of mares that had aborted. 3. Investigation of the outbreaks in this Province seems to indicate that the stallion plays an important part in the spread of the disease. However, further research is necessary in order to justify any of the existing theories of natural infection. Printed by WILLIAM BRIGGS, Toronto