482 



Report on Epizootic Abortion. [sept., 



alive in the open market. The latter custom is likely to 

 introduce disease to other establishments, unless the 

 animals have ceased to discharge; and they should be kept 

 for at least three months after abortion before being sent for 

 sale. 



The first custom is less objectionable than the second, but 

 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 

 animals, 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 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. 

 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— The Committee do not consider the bull a factor 

 of the first importance in the dissemination of abortion, but 

 infection by means of a contaminated bull must be looked 

 upon as a distinct possibility. There is, therefore, something 

 to be said in favour of keeping a bull for the service of cows 

 which have aborted, and, when that is not possible, of disin- 

 infecting the external genital organs of the bull after he 

 has served such cows. Of course, if the cows can be 

 immunised the same bull might be used for all. Cows from 

 a clean establishment should not 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. 



