Retained Placenta in the Cow 795 



The advent of cotyledonitis may vary in different cases. In 

 many instances, the disease of the placenta precedes the expul- 

 sion of the fetus, and consequently, at the time of the expulsion 

 of the calf, the pathologic conditions which must result in reten- 

 tion of the fetal membranes are already present, and fully devel- 

 oped. This is especially true in contagious abortion, in which 

 there is frequently more or less infection of the cotyledons, prior to 

 the expulsion of the uterine contents. If the abortion occurs 

 early in pregnancy, before the chorionic tufts have become de- 

 veloped, the fetal membranes are regularly expelled along with 

 the aborted fetus. I,ater in pregnancy, after the chorionic tufts 

 have become more developed, with corresponding complexity of 

 the maternal placenta, retained afterbirth becomes very common, 

 and is referable to the existence, at the time of the expulsion of 

 the fetus, of a distinct inflammation of the maternal placenta, 

 which incarcerates and holds the chorionic tufts of the fetal pla- 

 centa. In other cases, also, inflammation has already advanced • 

 into the uterus, and brought about an inflammation of the coty- 

 ledons, prior to the expulsion of the fetus. In the granular vene- 

 real disease of cows, where the granular inflammation extends 

 into the uterus, if tl)« death of the fetus fails to be brought 

 about, but instead its premature expulsion is caused, the cotyle- 

 dons readily suffer, and the expulsion of the immature fetus may 

 be followed by the retention of the membranes. 



When a pregnant animal has suffered for a long period of time 

 from prolapse of the vagina and of the vaginal portion of the 

 uterus, the uterine cavity is very prone to become infected, since 

 the chief barrier to uterine infection, the healthy vagina, has 

 been replaced by a diseased and infected organ. 



Similar conditions prevail when torsion of the uterus has oc- 

 curred, because compression and stretching of the tissues have 

 greatly decreased their power of resisting infection and permitted 

 the infection to extend into the uterine cavity and involve the 

 placenta. Any cause which may operate in such a way as to 

 permit the access of disease-producing organisms into the 

 uterine cavity may at any time cause infection of the maternal 

 placenta and bring about a degree of inflammation and swelling 

 which will eventually cause a retention of the fetal membranes. 



In the other important group of cases, those in which the dis- 

 eased condition occurs after the completion of birth, infection 



