Current views about causes and treatment of retained placenta in mares

One of the most frequent disturbances of parturition in mares is retained placenta. Physiologically the placenta should be expelled within 3h. The causes for retentio secundinarium are not clear, but usually weak myometrial activity, hormonal disturbances, placentitis and endometritis are considered highly probable. Metritis, pododermatitis, septicemia and even death can occur if correct therapy is not applied, but these consequences do not occur as often as it is thought. Data concerning the influence of retained placenta on pregnancy rate contain discrepancies for which different treatment schedules may be responsible. The latter include manual removal of afterbirths, flushing the uterus by means of disinfecting fluids, intramuscular or intravenous injections of oxytocin, calcium-magnesium solutions and infusions of collagenase into umbilical arteries and veins.