8o8 Veterinary Obstetrics 



which may be attracted to them, which brings about recovery. 

 If the infection of the cotyledons and of the uterine walls is of 

 such a character as to destroy the leucocytes, recovery cannot 

 occur. 



2. Retained Placenta in the Mare. 



Retention of the placenta is much less frequent in the mare 

 than in the cow. Clinically, retention of the placenta in the 

 mare is divisible into two separate forms, total and fragmentary. 



Total retention of the fetal membranes in the mare corre- 

 sponds in a measure to the disease in the cow. It is, however, 

 very rare, not only as related to placental retention in other ani- 

 mals, but also as compared with the fragmental retention in this 

 animal. 



The rarity of placental retention in the mare is explained upon 

 various hypotheses. Most significant, perhaps, is the compara- 

 tive simplicity of the chorionic tufts, so that any swelling of the 

 uterine mucosa does not tend materially to incarcerate them and 

 hold the chorion. It bears another important difference when 

 compared with ruminants ; the placenta is diffuse. The chorion 

 is thick, rigid, not readily compressible. When involution of 

 the uterus occurs, the area of attachment in the uterine mucosa 

 rapidly decreases, while the opposing chorionic attachments are 

 not subject to like diminution in area and are consequently de- 

 tached. The placentae of sheep and goats are essentially as intri- 

 ate as those of the cow, and are upon the same general plan, but 

 retention of the fetal membranes in these is very rare as com- 

 pared with the cow. According to our observations also the dis- 

 ease is less common in the ewe than in the mare. Hence the 

 arrangement of the placental structures does not wholly control 

 the probability of retention. 



The causes of total placental retentiou in the mare are analo- 

 gous to those already mentioned in the cow, such as placentitis 

 as an accompaniment of contagious abortion, and fatigue of the 

 uterine walls during difiicult labor, followed by infection. 



The symptoms of total placental retention in the mare usu- 

 ally consist merely of the visible protrusion from the vulva of 

 the umbilic cord and portions of the chorion. There is rarely 

 any straining. If neglected, and infection occurs, as it does very 

 quickly, a diffuse endometritis quickly follows, the chorion usu- 



