LECTURE LIV 

 OBSTETRICS— Continued 



Infectious Abortion" 



In many respects, infectious abortion is the most serious dis- 

 ease confronting the American breeder. Those responsible for 

 its control are confronted with many and serious difficulties. 

 The disease is insidious, the period of incubation being rather 

 long. There is no satisfactory means of individual diagnosis 

 and prevention is uncertain. Management of an infected herd 

 is tedious, expensive, and results often unreliable. 



Causes. — Infectious abortion is due to living microorganisms, 

 usually bacteria. It is evident that several different germs are 

 capable of causing this trouble, and if this be true, then we do 

 not have a specific disease due to one specific germ. It is most 

 common in cattle at five to seven months, but may occur at 

 any time after a few weeks of pregnancy. Cattle, horses, sheep, 

 and swine are all subject to an infectious abortion, due to 

 several different microorganisms. The virus generally accepted 

 as being chiefly responsible for abortion in cattle and swine (the 

 Bacillus of Bang) appears to be the same, although the disease 

 apparently does not spread from the one class of stock to the 

 other. In mares and ewes, however, the viruses are different. 



The student should remember that the act of abortion is only 

 one of several disastrous symptoms, as taught in the preceding 

 Lecture, and not in itself a complete disease. 



Abortion in horses, swine, and sheep is less common and less 

 serious than in cattle at present, and this Lecture will treat 

 chiefly of infectious abortion in cattle. 



It is evident that infectious abortion may be spread in many 

 ways. It is most easily introduced by the purchase of an in- 

 fected pregnant cow from a herd in which the disease has pre- 

 vailed. A cow may abort one or more times, then become more 

 or less immune and subsequently carry calves to full term, but 

 remain infectious for an indefinite period, and thus prove a 



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