CUTTING EDGE, NEW TOPICS, AND PRACTICAL INFORMATION IN THERIOGENOLOGY
Fig. 7. The intact (edematous) placenta is removed 10 minutes after water infusion of the umbilical vessel.
ine lavage) fail. Because of the need to safely remove fetal membranes by 6 hours post-partum, removal using umbilical vasculature infusion was investigated. Traditional manual removal of fe- tal membranes in mares (manual separation of the chorioallantois from the endometrium combined with twisting of the membranes) is controversial because of the risks of hemorrhage, impaired uter- ine involution, tearing of the placenta, damage to the endometrium, and uterine prolapse. Similar complications were not noted in mares undergoing umbilical vasculature infusion. The degree with which the membranes were attached, as well as the duration of membrane retention, can affect the outcome of manual membrane removal using any procedure.
In the described procedure the infusion of water
into the allantochorion via the umbilical vasculature appears to induce edema and swelling of the tissue (Figs. 7 and 8). It is postulated that the placental microvilli stretch under pressure causing separation of the fetal membranes from the endometrium. The weight of the placenta concurrently increases (but is controlled by support from the veterinarian) and which may also enhance the separation. Fluid may also “leak” into the space between the chorion and endometrium, thus facilitating further mem- brane separation. In 2014, four placentas were examined histologi-
cally after performing this procedure. In addition, five normal placentas were infused with water or saline and samples for histology were collected be-
Fig. 8. Severe edema in the submucosal layers and absence of erythrocytes in the vessel lumina after 5 minutes of water influx. 482 2015 Vol. 61 AAEP PROCEEDINGS
