Endocrine Aspects of Uterine Involution in the Cow

Abstract

AbstractThe postpartum period (PP) (=puerperium) is characterized by involution of the uterus and recyclicity of the ovarian functions to prepare the animal for a new pregnancy period. The time required for the genital organs to become normalised is influenced by breed, management including feeding regimens and environmental factors. This period is also strongly influenced by periparturient diseases such as dystocia, paresis (puerperalis), mastitis, endometritis, etc. The period is also influenced by several hormonal changes. During the postpartum period in the cow, a massive release of PGF2α occurs concomitantly with the uterine involution. In cows with retained foetal membranes (RFM), a second pulsatile release of PGF2α is seen concomitant with the growth and final elimination of bacteria. A similar pattern is seen in cows with induced parturitions with e.g. dexamethasone, indicating the occurrence of RFM/endometritis as a consequence of the induction. The duration of these prostaglandin releases are negatively correlated to uterine involution in normal cows and positively correlated in cows with RFM/endometritis respectively. As long as the release is maintained, the cow is unable to ovulate and it therefore seems likely that PGF2α or other products in the arachidonic acid cascade can inhibit the ovarian activity. Onset of ovarian cyclicity influences to a high degree the uterine involution, however most common is that the first ovarian cycle is shorter than seen during the normal oestrous cycle. The uterine involution process can be enhanced by treatments with exogenous PGF2α‐ No effect on uterine involution in healthy cows, or a slight positive effect, is seen after treatment with prostaglandin synthesis inhibitors (e.g. flunixin meglumine). The aim of this presentation is to review some of the knowledge of the interactions between the uterus and ovaries during the postpartum period in cattle.