794 Veterinary Obstetrics 



Retention of the fetal membranes in the cow is due primarily 

 to the incarceration of the tufts of the chorion within the crypts 

 of the maternal cotyledons. 



Recently Pomayer,' in a very extended study, has quite well 

 shown the principal causes of retained afterbirth by histologic 

 research, and his findings and conclusions are in full accord with 

 clinical experience. Pomayer holds that retained fetal mem- 

 branes are due to inflammation and swelling of the maternal pla- 

 centa, that is, placentitis or cotyledonitis. The lesions within 

 the cotyledons may be of two classes, aseptic and septic. 



During pregnancy an animal may receive a blow, be gored by a 

 cow, or meet with some other external injury which may more 

 or less detach some portion of the chorion from the maternal pla- 

 centa. Hemorrhage may take place to a limited degree, followed 

 by a more or less extensive inflammation, with new formation of 

 connective tissue between the mucous membrane of the placenta 

 and the epithelial tufts of the chorion. Should the hemorrhage 

 between the two parts become very great, it may cause so exten- 

 sive a separation as to induce the death and expulsion of the 

 fetus. If the hemorrhage is not so great, and the inflammatory 

 processes already mentioned take place, the fetal membranes may 

 become more or less incarcerated and held over a limited area, 

 but there would be no general retention of the entire fetal mem- 

 branes, or rather we would say that, in the cow, the fetal mem- 

 branes would become readily detached from all the cotyledons 

 save one or two which had been implicated in the injury during 

 pregnancy. With this group of cases, we have little to do, and 

 clinically it is virtually negligible. 



The important group, from the practitioner's standpoint, con- 

 sists of those cases in which infection plays the chief role and 

 the retention of the afterbirth is finally maintained by the in- 

 flammation of the maternal placenta. By observing Figs, yg and 

 139, it will be seen how intimate is the relation between the chorion 

 and the cotyledons in the cow, and it will be readily understood 

 that, when the cotyledons become inflamed and swell, the very 

 complex chorionic tufts may become more or less immovably 

 fixed and held. 



' Das Zuruckhalten der Nachgeburt beim Rind, by Dr. Phil. C. Pomayer. 



