Canine placentation: normal gross and histologic structure, and confounding features of evaluation

Abstract

Striking microscopic changes take place in canine endometrium morphology during placentation. Gross structure (zonary placentation) and nature of maternal-fetal interface (endotheliochorial) is generally well understood. However, histological changes in endometrial tissue proper and how they impact fertility assessment utilizing histology may be less well understood. This review will cover evaluation of canine placenta (gross and microscopic), difficulties in correlating histologic evaluation to fertility and fetal loss, and implications in interpreting histopathology results.