[The significance of steroid hormones and prostaglandins for the expulsion of the afterbirth in cattle].

This review describes the importance of different hormones (oestrogens, progesterone, prostaglandins and glucocorticoids) for the loosening process of the foetal membranes in cattle. Hormone concentrations, measured ante partum and at the time of parturition are discussed. In the literature conflicting results can be found. Foetal membrane retention seems to coincide with increased plasma progesterone and decreased plasma oestrogen and PGF2 alpha concentrations. Possible effects of particular hormones on loosening of the placenta are discussed. It can be concluded that these hormones do have a considerable influence on the foetal membranes. However, to clarify their definite role for retention of the placenta further investigations are needed.