CONTAGIOUS ABORTION OF COWS TEXT

The principles of bacteriological nomenclature have not as yet been universally adopted, and most of the investigators quoted in this paper have avoided the use of a specific name for the abortion bacillus. Bang himself seems not to have given it a binomial designation, but he repeatedly employed the term "Abortusbacillus" as a specific term. Chester (1901) has named the organism "_Bacterium abortivum_" with the synonym "Bacillus of contagious abortion in cows, Bang." Preisz (1902) suggested the name "_Corynebacterium abortus endemici (s. infectiousi)_." This generic name Corynebacterium appears to be incorrect, as the organism is very different from those to which this name has been previously applied. It would seem best to employ the more general term Bacillus (or Bacterium) as a confessedly temporary generic name until a more definite generic nomenclature of bacteria shall have been developed and generally adopted. In determining the specific name it would seem that the term "Abortusbacillus" employed by its discoverer as early as 1907 should receive first consideration. We[1] have therefore suggested the name _Bacillus_ (or _Bacterium_) _abortus_, Bang, for this organism. The term "_abortus_," being in the genitive case, may be employed with either generic term. FOOTNOTE: [Footnote 1: MacNeal and Kerr, 1910.] RESTRICTION AND ERADICATION OF THE DISEASE Reliable methods for restricting the spread of contagious abortion and for eradicating it from a herd may be expected as the result of more complete and accurate knowledge of the nature of the disease and its mode of spread. Some of these methods, such as that of artificial immunization, are being tested experimentally by the Departmental Committee appointed by the British Board of Agriculture and Fisheries to inquire into Epizootic Abortion. Until these methods have been developed beyond the experimental stage, the older more or less empirical methods will have to be relied upon. Fortunately these older methods can now be subjected to careful scrutiny in the light of modern knowledge of the disease, and they have been studied in this way by the British Committee mentioned above. The following summary has been copied, with only slight abridgment and very few alterations, from the report of this Committee. "The methods which have been relied upon in the past for the prevention of abortion and its eradication from a herd are:-- (1) Periodical spraying of the external genital organs and hind quarters with disinfectant solutions. (2) Isolation of animals as soon as they show the premonitory signs of abortion. (3) Internal administration of carbolic acid to animals supposed to be infected or exposed to infection. (4) Irrigation of the genital organs of animals which have aborted with antiseptic solutions. (5) Removal and disposal of animals which have aborted. (6) The keeping of a special bull for serving animals which have aborted, or, what is based on the same idea, the disinfection of the external genital organs of the bull with antiseptic solutions after he has served such a cow. (7) Destruction of the abortion membranes, and disinfection of the parts of the buildings, litter, etc., with which the infective material has come in contact. (8) The keeping of a goat, especially a male goat, in a byre with the cows." It cannot be said of the above measures that either singly or collectively they have brought about any material improvement in the general condition of our herds in relation to abortion. According to reports, decided improvements have been effected in individual herds by the adoption of isolation and disinfection, while in others very little has been accomplished. Some of the above methods are founded on nothing more than ignorant empiricism, while others are based upon pathological and physiological considerations which are only partially correct in their applications. Since most of them have obtained a certain amount of hold, at least on the minds of stockowners, it may be useful to discuss each measure separately in the light of our recent investigations. _Spraying of the External Genital Organs._--This is a procedure which probably has little or no value. (_Abridged._) _Isolation of Animals as soon as they show Signs of Abortion._--The necessity for this measure is obvious, and its importance cannot be too much insisted on. An infected animal only becomes infective to others immediately before the act of abortion, and may remain so for some weeks afterwards. However, only a proportion of the affected animals show premonitory signs, and quite a number may abort amongst their companions without warning. Under such conditions, then, measures of immediate isolation lose much of their undoubted theoretical value, owing to the difficulty in the way of carrying them out in practice. There is not likely to be any serious difficulty in diagnosing the bacterial disease after an act of abortion, even in an isolated case, if the membranes are available in a reasonably fresh state. (_Abridged._) Isolation of the affected animals, however, must be complete before and after the act to be of any real value. Having regard to what appears to be the most common form of infection, viz., by ingestion, we do not think that anything material is to be gained by merely putting all the cows about to abort and those which have aborted at the lower end of a byre, so that the infective discharges may not come in contact with the external genital organs of their fellows, unless we assume that infection frequently takes place by an animal licking virulent material from a part of its body where it has been deposited by flicks of the tail which has been contaminated by lying in the gutter behind the stalls. _Internal Administration of Carbolic Acid._--The uselessness of carbolic acid and other antiseptics as curative agents has already been referred to. As a preventive agent by internal administration we believe carbolic acid to be equally useless. Even if it were possible to administer very large doses of this poisonous substance, one could not expect to be able to give enough to destroy the bacilli which have been swallowed and mixed with the contents of the enormous stomachs and intestines, and it would be equally hopeless to expect to destroy in this way the bacilli which have already reached the womb. This alleged measure of prevention must be regarded as an absurdity which has gained a certain amount of support owing to observations carelessly collated and carelessly interpreted. _Irrigation of the Genital Passages after Abortion._--With the act of abortion the greater part of the uterine exudate is immediately ejected. That some of it remains behind for a short period is certain, since we were able to demonstrate abortion bacilli in material obtained from the vagina of a heifer three days after she had aborted. On the other hand, no abortion bacilli could be found in the uterus of another heifer a month after she had aborted. It seems probable that, as a rule, the genital organs cleanse themselves by natural means a comparatively short time after abortion has taken place. Almost immediately after abortion and expulsion of the membranes the uterus contracts, and its internal surfaces come into apposition. Its condition is such that it would not be possible to force fluid into it with a pump from the vagina. Apart then, from the probability that disinfection of the uterus by antiseptics is not necessary to rid the organ of abortion bacilli, we are of opinion that it is futile to attempt it by irrigation methods. So long as a discharge continues to come from the genital passages, we think that for hygienic and therapeutic reasons they ought to be cleansed once or twice by the intravaginal injection of tepid antiseptic solutions, such as a 2 per cent solution of carbolic acid or a 1 in 3,000 solution of corrosive sublimate, but not on the ground that the injections will disinfect the uterus. We are of opinion that it will seldom be necessary to continue the injections for more than a month, and that after three months there should be small risk in putting the cow to the bull, provided she is afterwards protected from fresh infection. _Removal and disposal of Animals which have aborted._--It is quite a prevalent custom to feed for the butcher cows which have aborted. It is also customary to sell such cows alive in the open market. The second custom we consider likely to introduce disease to other establishments, unless the animals have ceased to discharge; they should, we think, be kept for at least three months after abortion before being sent for sale. The first custom is less objectionable than the second, but we think that a breeder will be more likely to get rid of abortion from his herds by keeping such animals than by disposing of them and bringing in new ones before his entire herd is free from the disease. There can be no doubt that in most cases an attack of the disease greatly increases an animal's resistance to future attacks, and that in a large proportion of the affected, probably in the majority, this resistance is sufficient to fortify them against infection during their next pregnancy. It is beyond doubt that a considerable proportion may abort twice in succession, but it is not improbable that inoculation methods may now be successfully employed to exalt their resistance. In the midst of infection there is no better guarantee against the disease than the possession of an immune stock, and for this reason we consider that on infected premises the animals which have already aborted are to be looked upon as valuable assets for purposes of eradication, much more valuable than the new and susceptible animals brought in. We find, however, that a small proportion of cows will not hold to the bull for an indefinite period after abortion, and it may be found better to fatten off such animals, unless they are of high value. _The Keeping of a Special Bull for Cows which have aborted._--We have already stated that we do not consider the bull a factor of the first importance in the dissemination of abortion but that infection by means of a contaminated bull must be looked upon as a distinct possibility. We think, therefore, that there is something to be said in favor of keeping a bull for the service of cows which have aborted, and, when that is not possible, of disinfecting the external genital organs of the bull after he has served such cows. Of course, if the cows can be immunized the same bull might be used for all. We do not think that cows from a clean establishment should be sent even to a clean bull on infected premises, and it is also inadvisable that cows from infected premises should be sent to a bull on a clean establishment. _Destruction of Virulent Material and disinfection of everything contaminated by it._--The immediate disinfection of the virulent materials and contaminated objects is of great importance, more especially as it appears that the natural virus may remain active for a long time outside the body. The soiled litter, dung, exudate, membranes, and fetus should all be removed at once, preferably after they have been treated with caustic lime. After removal they should be soaked in paraffin and burned, or buried in a deep pit, preferably the former. On no account should the fetus and membranes be fed to pigs or dogs. When a fetus is aborted alive, as sometimes happens, it seldom survives long, and it is advisable to kill and destroy it, since it may excrete abundance of virulent material from its intestines if allowed to live. If, however, it be decided not to kill it, it should immediately be isolated. The walls of the stall and the floor should be washed or strewn thickly with caustic lime, or drenched freely with boiling water. The temperature necessary to kill the bacillus is not great, and this simple method of disinfection should prove efficacious. Lastly, the boots, clothing, and hands of attendants should be disinfected by making use of any reliable disinfectant, such as 3 or 4 per cent solution of carbolic acid. _The keeping of a Goat amongst the Cows._--This, we believe can only have had its origin in ignorant superstition, but we feel bound to mention it, as the question of its efficacy has quite frequently been seriously put to us. We would point out that goats themselves can be infected with cattle abortion, and that both male and female goats were on our premises during the greater part of the time occupied with the cattle experiments, and their presence did not prevent animals from aborting. _Preventive Inoculation._--This is still in the experimental stage and definite results are hoped for. (_Abridged._) The Committee refrained from making any recommendations in regard to measures to be taken by the Board of Agriculture and Fisheries for the prevention of the disease. Experience in connection with the beef cattle herd at the Illinois Agricultural Experiment Station with the methods of isolation, careful disposal of infected material, cleaning and disinfection of infected stalls, antiseptic irrigation of the genital passages of cows which had aborted, and antiseptic irrigation of the bull before and after service, together with the use of a special bull for heifers and clean cows, has been very satisfactory. These measures were applied under the direction of Professor H. W. Mumford and Mr. H. O. Allison. During the year previous to the inauguration of these measures a large percentage of the calves were lost by abortion. A decided improvement in respect to the number of calves saved was coincident with the use of the procedures mentioned above. They were applied to each case of abortion as it occurred, until in the course of two years abortions have become very infrequent and the herd is now considered free from the disease. It should be noted, however, that those cows which had aborted were not necessarily disposed of, but after local irrigation treatment until the discharge had ceased, they were bred again. Some of the improvement in the herd has, therefore, doubtless been due merely to the retention of relatively immune cows. Altho the experience here has been rather fortunate and the results obtained seem to bear some relation to the employment of the measures deemed worthy by the British Committee, we hesitate to state that there was any necessary relation between them, because cattle men have observed somewhat similar improvement in herds without the use of any treatment at all. In other words, there appears to be a tendency for the disease sometimes to die out in a herd or to become quiescent for a year or two. On the other hand, the recommendations of the British Committee supported as they seem to be by our local experience, certainly warrant the recommendation of these measures for use in combating contagious abortion. In any event good results cannot be expected without intelligent, careful, and painstaking work, and it may be that some of the failures in applying these measures have resulted from lack of efficiency in applying them rather than from insufficiency of the measures themselves. References 1. =Bang.= Die Aetiologie des seuchenhaften ("infectioesen") Verwertens. Ztschr. f. Thiermed. 1: 241-278. 1897. 2. =Board of Agriculture and Fisheries= (Great Britain). Report of the Departmental Committee to inquire into Epizootic Abortion. Part 1. Epizootic Abortion in Cattle. London, 1909. 3. =Chester.= A Manual of Determinative Bacteriology. 1901. 4. =McFadyean and Stockman.= Epizootic Abortion. Report. Dept. Com. Bd. Agr. and Fisheries. (Gt. Brit.), Appendix to Part I, 1909. Review in Expt. Sta. Record =22=: 584-586. 1910. 5. =MacNeal= and =Kerr=. Bacillus abortus of Bang, the cause of contagious abortion in cattle. Jour. Infect. Diseases =7=: 469-475 (1910). 6. =Nocard,= Review by =Bang=. Ztschr. f. Thiermed, =1=: 243-246. 1897. 7. =Nowak.= Le bacille de Bang et sa biologie. Annales de l'Institut Pasteur =22=: 541-546. 1908. 8. =Preisz.= Der Bacillus des seuchenhaften Verwerfens. Centralbl. f. Bakt. etc., I Abt. Orig. =33=: 190-196 (1903). 9. =Zwick.= Ueber den Erreger des infectioesen Abortus des Rindes. Centralbl. f. Bakt. etc., Beilage zu I Abt. Ref. =47=: 219-220. 1910. * * * * * +-----------------------------------------------------------+ | Transcriber's Note: | | | | Bold text is marked =like so= in the text version of this | | document. | | | +-----------------------------------------------------------+ * * * * * End of Project Gutenberg's Contagious Abortion of Cows, by Ward J. MacNeal