ACCIDENTS INCIDENTAL TO PREGNANCY 267 



high-breeding bringing in its train greater liability to certain accidents 

 incidental to pregnancy and parturition. High-bred animals therefore 

 require more careful supervision on the part of the breeder. 



Abortion. Abortion and premature birth are the most serious accidents 

 that can happen to pregnant mares. Though both terms are often applied 

 indiscriminately, "slipping the foal" is the term generally employed when 

 the young creature is expelled at any time before it is fully developed and 

 the usual time of pregnancy has expired; yet it is recognized by those 

 who make this subject their study that the term " abortion " should imply 

 expulsion of the foetus from the mother when it has not attained sufficient 

 development to live outside its mother's body, while " premature birth " 

 signifies that the young creature has been born before its time, yet with all 

 its organs sufficiently formed to enable it to live for at least some time in 

 the external world. In the first instance it is either dead when expelled 

 from the uterus or it dies immediately afterwards; and in the second it 

 may be weakly and immature and succumb after a variable period, or it 

 may continue to live and eventually thrive. In practice, however, there is 

 no accurately defined limit between abortion and premature birth, and 

 especially when the latter has been brought about by any one of the causes 

 that produce the former. 



Abortion is said to take place in mares when the foetus is expelled forty 

 days before the usual period of pregnancy has terminated, and though it 

 may occur at any time during pregnancy, especially before the 300th day, 

 yet it is much more frequent during the first than the second half of preg- 

 nancy. When the accident takes place at a very early period it may not 

 produce any appreciable disturbance in the mare's health, and the develop- 

 ing ovum usually escapes intact and often unperceived; but when it 

 occurs at a later stage it is serious, as it not only entails the loss of the 

 foal, but may also compromise the health, or even the life, of the parent. 



Many causes operate in bringing about abortion, and some of these 

 have been mentioned; they act more or less in a mechanical manner, and 

 usually only one mare in a number will abort. But when several cases 

 follow each other quickly in a breeding establishment, and no sufficient 

 reason can be assigned for their occurrence, then the question of infection 

 arises, and there can be no doubt now that to this cause must be ascribed 

 the serious outbreaks of abortion among mares in recent years in various 

 parts of Europe, but more especially in the United States of America, 

 where heavy losses have been sustained. 



When, therefore, two or three abortions happen in a stud, it is well to 

 adopt precautions at once; indeed, where a number of pregnant mares are 

 kept, such precautions ought to be resorted to when only one accident of 



