APPLICATIONS OF VETERINARY RESEARCH. 
Applications of Veterinary Research: With an Example. 
By Prof. HAROLD A. WOODRUFF. 
(IL) 
About this time Schroeder and Cotton*, two workers in the United States, 
recorded the occurrence of the abortion bacillus in the milk of cows. On inves- 
tigation this was found to be a frequent occurrence, and Seddon has shown’ that 
in infected dairy herds in Victoria a considerable proportion of cows are voiding 
abortion bacilli in their milk. ‘Further it is found that these animals may 
continue to eliminate the specific bacilli for many months, or even years, during 
normal pregnancies or sometimes accompanied by abortions. Apart from the 
act of abortion there are practically no symptoms, so that, judged by this 
criterion, there are many “carriers” of the infection and comparatively tew 
active eases. That a large number are carriers is proved by (1) their positive 
reaction to the agglutination test, and (2) the discovery of the abortion bacillus’ 
in their milk. : 
The recovery of the bacillus from milk is effected by injecting a small quan- 
tity of milk into the peritoneal cavity of a guinea pig. In four to six weeks’ time’ 
a pure culture of abortion bacillus can be obtained from the animal’s spleen. 
Thus the large number of positive reactions to the agglutination test is quite 
well explained, and the test may be looked upon as a reliable guide to determine 
infection or non-infection, 
A practical application of the test is of great value in determining whether 
a herd is free from the disease at a particular time, and thereafter all fresli 
purchases and newcomers to the herd can be tested before being allowed to mix 
with clean animals. For the test, there is required about 2 ozs. of blood from 
the suspected animal, this material being sent to the bacteriological laboratory, 
where the diagnosis can be made in 24 hours. 
Thus it can be claimed that scientific research has solved ion of the basic. 
problems connected with the disease, namely, its specific cause, and reliable 
means of diagnosis at all stages of the infection.+ 
But a further important question now arises, namely, what are the common 
methods of infection? 
In the first place, it may be stated, with some degree of confidence, that the 
disease is a purely contagious one due to an obligatory parasite. The organism 
of contagious abortion is cultivated artificially with some difficulty, and under 
special conditions, so that all the available evidence is against its being able to 
live and multiply naturally outside the animal body. Thus when contagious 
abortion breaks out on a farm it can only be as a result of infection from a 
precedent case of the disease. 
In the second place, it appears likely that there is more than one method 
nf transmission, For many years it was believed that the exclusive means of* 
natural infection was by the bull in the act of copulation: But McFadyean 
and Stockman first showed that animals could easily be infected by the inges- 
tion of infected material, such as discharge from a cow after abortion. Further, 
it is quite common to find virgin heifers which react to the agglutination test, 
and in these cases infection by ingestion must be considered the explanation. 
*The Bacillus of Contagious Abortion found in Milk. U.S. Dept. of Agriculture, Bureau of Animal 
Industry, Circular, No. 216. 
+ In experimentally infected animals the agglutination test will be found reliable within-10 days of the 
time of infection. : 
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