796 Diseases of the Genital Organs 



uterine contractions with the prompt expulsion of the fetal 

 cadaver. 



Intra-uterine infection is more certain to cause abortion 

 in the mare than in any other domestic animal. Since the 

 cervix is shorter and its canal more dilatable, less power is 

 demanded of the uterine walls to force the fetal - cadaver 

 into the cervical canal, at which point the abdominal walls 

 assume the chief burden of emptying the uterus. The ana- 

 tomical features of the placenta confine the infection, at least 

 temporarily, to the cervical end, as indicated in Fig. 230, 

 concentrate the uterine irritation more definitely at the cer- 

 vical end, and leave the ovarian end free from disease and 

 competent to contract vigorously upon the uterine contents. 

 These anatomical differences modify interesetingly the clini- 

 cal behavior of intra-uterine infection. While it is not rare 

 for a bovine fetal cadaver to undergo partial or complete 

 maceration in the uterus, it is exceedingly rare to observe 

 this result in the mare. The mare is in some respects more 

 vulnerable to sepsis than the cow, but if this plays any part 

 at all it is a minor one. Fetal cadavers (except at or near 

 full term) almost never undergo putrid decomposition in 

 the uterus of the mare, but are practically always expelled 

 promptly. When fetal death occurs at or near full term, the 

 condition is essentially alike in mare or cow. It is common 

 in both species, especially when the fetus presents by the 

 breech, for fetal death and emphysema to occur without 

 visible effort at expulsion. The phenomenon of abortion in 

 mares, as one of the results of intra-uterine infection, has 

 long been an important economic problem in horse-breeding 

 and up to the present time no outstanding progress has been 

 made in its control. 



Abortion of mares first acquired prominence in the United 

 States about 1886, when it appeared in several states in the 

 Mississippi Valley, in which horse-breeding had become a 

 very important industry. It soon acquired a very extensive 

 distribution and high degree of virulence. The unorganized 

 state of veterinary science in the United States prevented 

 the recording of any definite statistics in reference to the 



