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Biological Therapy 



B. abortus can generally be demonstrated in the milk of such 

 animals whereas any vaginal discharge during or following 

 pregnancy is badly contaminated. Such animals even though 

 they do not abort are a prolific source for the spread of the 

 disease. 



It is fortunate that, contrary to former beliefs, calves 

 suckling infected cows do not become permanently infected 

 even though they ingest large numbers of B. abortus in the 

 milk. If such calves are maintained in a manner which 

 prevents their contact with infectious material after wean- 

 ing they will mature as healthy individuals. The percentage 

 of animals raised in this manner which later react to an 

 agglutination test is no greater than those which nursed 

 healthy dams. 



SYMPTOMS 



A premature expulsion of the fetus is ordinarily the 

 first symptom which is observed. This may occur at any 

 time between the third and the seventh month of pregnancy. 

 This abortion is generally followed by vaginal discharge, 

 retained placenta, metritis and in some instances by sterility. 

 Although these complications are caused by bacteria of sec- 

 ondary etiological significance, the damage which they oc- 

 casion is as serious as the abortion itself, since the subse- 

 quent breeding efficiency is seriously impaired. 



DIAGNOSIS 



This is most accurately obtained by the agglutination 

 test. For this purpose a few cubic centimeters of blood from 

 affected animals should be obtained. This should not be 

 defibrinated but should be allowed to coagulate. The test 

 is quite accurate and should be used as a herd rather than an 

 individual index. All animals which have aborted may not 

 react to this test nor does a positive reaction insure an im- 

 pending abortion on the part of the reactor. Schroeder has 

 aptly summarized this condition as follows: ''An abortion 

 is, strictly speaking, the supreme or superlative event in 

 bovine infectious abortion and not the essential event. We 

 may reasonably say that as all children attacked by diph- 

 theria do not die, so all cows attacked by bovine infectious 

 abortion do not abort." However, if a positive reaction is 

 obtained from any of the herd members the entire herd should 

 he handled as though infected. 



