430 THE DAIKYMAN'S MANUAL. 



ABORTION. 



This disease is one of the most injurious of those 

 which affect dairy cattle. It has heen considered a mys- 

 terious disorder and much investigation has been devoted 

 to its causes and progress without any very certain result 

 until the present time. It is called abortion in the 

 cow when the foetus is expelled before the seventh month 

 and before it has been sufficiently developed to maintain 

 an existence separately from the dam. After this period 

 the expulsion of the foetus, whether it be living or dead, 

 is called premature birth. This period has been fixed 

 by veterinarians, as well as by physicians, as the connect- 

 ing limit between these two forms of accidents of preg- 

 nane}^, because after the 200th day the foetus becomes 

 capable of a separate existence, and may live and thrive, 

 under exceptionally favorable circumstances, although at 

 first weakly or immature. 



Premature birth, too, can scarcely be considered a 

 disease, but rather in the light of an accidental occur- 

 rence due to various causes, while abortion is undoubt- 

 edly a disease originating in certain disordered conditions 

 of the animal, which can be traced to a specific cause or 

 result of causes. It may be classed as of two kinds, 

 sporadic or enzootic, and epizootic, infectious, or conta- 

 gious. The former maybe due to several causes, ex- 

 ternal and internal; the latter is always due to infection 

 by a specific germ introduced into the system and devel- 

 oped by favorable circumstances. 



Sporadic or Accidental Abortion. — The causes 

 of accidental abortion are very numerous, acting either 

 directly or indirectly, and produce their effects in an 

 evident or obscure manner. 



The External Causes are physical injuries arising 

 from falls, blows, severe exercise, as being chased by dogs 

 07 other cattle, continued bad weather and exposure to 



