470 Veterinary Obstetrics 



It maj' be that the two fetuses in some way cause mechanical 

 injuries to each other during movements of the mare and thus 

 induce some injury to the placenta and lead to fetal death. 



Psychic influences are claimed by some to induce abortion in 

 rare cases. Cases have been related where mares have aborted 

 immediately after suffering greatly from fright, but even here it 

 may be that some physical injury resulted because of the fright. 

 It has been stated by various writers that, if one animal in a 

 stable aborts, the sight of the accident may cause neighboring 

 females to also abort. Harms very properly remarks that, if 

 such a view were correct, an animal giving birth to young at the 

 regular time in the presence of other pregnant females should 

 cause them to abort. So far as our literature indicates, it would 

 seem that psychic influences play a very small part in the 

 problem of abortion. Large herds of cows, ewes, mares and 

 sows are permitted to regularly give birth to their young in the 

 presence of the other pregnant animals, without visible danger 

 of inducing abortion or premature birth. Simultaneous births 

 in a herd may usually be regarded as coincident rather than con- 

 sequent. 



The castration of pregnant females usually causes abortion, 

 although such a result is not inevitable. The danger of abortion 

 following castration is sufficient to coutra-indicate the operation 

 in pregnant animals where it is probable that the accident would 

 imperil the life of the mother. In some animals, like the bitch, 

 we habitually remove the fetus and uterus at the time of castra- 

 tion, so that the question of possible abortion does not concern us. 



Mechanical irritations of the os uteri and vagina are said to 

 endanger the life of the fetus, but we have insufficient data to 

 clearly indicate the degree of risk. In practice we ordinarily 

 make manual explorations of the vagina, in our larger pregnant 

 animals, without any apparent danger. We recall one case in 

 which the owner of a valuable brood mare examined her per 

 vaginam because he believed she was not in foal. He dilated 

 the cervical canal and discovered the fetus, which he mistook for 

 a tumor. Later I was called and found the fetus, about 12 inches 

 long, still alive. Soon after this examination, the mare aborted. 

 This, however, does not show that examination of the vagina in 

 pregnant mares is dangerous, but merely that when the hand is 

 passed beyond into the uterus, where it eventually disturbs the 



