480 Report on Epizootic Abortion. [sept., 



importance of infection resulting from the more or less 

 accidental admission of infective material from the floor or 

 dirt of the cowshed, it must be borne in mind that, even when 

 discharges from an infected cow do reach the floor or become 

 mixed with the excreta in the channel behind the cows, the 

 chances must usually be against the bacilli gaining entrance 

 to the genital passages, and that the number of bacilli which 

 could be so admitted to the vulva or vagina under ordinary 

 conditions must generally be small. Infection by means of 

 the bull, though it may occur, is regarded as probably rare. 



Immunisation. — After discussing the symptoms and 

 diagnosis of the disease, the Committee describe the attempts 

 made to produce immunity by the inoculation of large doses 

 of pure culture. The pure. culture of the abortion bacillus 

 when injected into non-pregnant animals seemed quite 

 harmless, and the experimental results with heifers were 

 encouraging. An endeavour will be made to induce owners 

 of infected herds to try this method under the supervision 

 of the Board, with a view to obtain an idea of its value 

 as a practical measure in fighting epizootic abortion. It is 

 also proposed in the same way to test the effect of sub- 

 cutaneous injections of dead bacilli, and the results of both 

 these experimental investigations will be dealt with in a later 

 report. 



Methods of Prevention and Eradication. — The Com- 

 mittee then proceed to discuss the methods which have been 

 relied upon in the past for the prevention of abortion and its 

 eradication from a herd, and their conclusions are briefly as 

 follows : — 



Spraying of the External Genital Organs. — This is done 

 on the assumption that virulent material may at intervals 

 come in contact with the external genital organs. It is, 

 however, highly improbable that infection can take place 

 through the agency of virulent material which has been 

 merely deposited on or about the external genital organs, in 

 addition to which, to be effectual, any bactericidal agent 

 would require to be applied to the material almost at the 

 moment when it comes in contact with the genital organs — 

 an impossible thing to accomplish by periodical spraying. 

 This method, therefore, is useless so long; as trie animals 



