Retained foetal membrane and metritis


A detailed history for the veterinarian is necessary – including the age of the mare, past reproductive history, the time when the foal was delivered, whether the foaling was assisted, if any complications arose during delivery and if any medications were administered. A thorough examination of the mare and the placenta, if available, should then follow.

Retained Foetal Membranes

Foetal membranes are considered retained if they are not expelled within 3 hours of foaling. Membranes are retained in approximately 10% of mares, with a higher incidence noted in the heavier breeds e.g. Friesian, Clydesdale. Mares that have undergone abortion, foaling difficulty, caesarean, prolonged pregnancy, placentitis, hydrops and induction are all at higher risk. Mares with a history of retained membranes and those over 15 years of age may also be considered more susceptible.

The non-pregnant horn of the uterus is the most common site affected. The most likely cause is a disturbance in normal uterine activity and delayed uterine involution.

Clinically, the owner will see the presence of placental tissue protruding from the vulva. It may be dragging on the ground or only a small portion might be visible. Always examine the placenta following foaling, paying special attention to the tips of the horns. If the placenta is torn, look closely to see if any sections are missing. If you cannot visualise the placenta in its entirety, it must be assumed that the mare has retained a portion and she should be treated accordingly. If retained membranes remain untreated, the consequences can be dire – encompassing metritis, laminitis and possible death. Please note that laminitis can occur secondarily to toxic metritis with or without the retention of membranes.

Membranes that are hanging at the hocks or below should be tied in a knot. This avoids further tearing should the mare stand on them. If the mare has retained the membranes for two hours or less, repeated injections of low dose oxytocin given intramuscularly may be sufficient to resolve the problem. However, if oxytocin therapy has not been successful, cautious manual removal of the membranes may be necessary. Clinical evaluation of the mare prior to proceeding with this procedure is essential and it should only be performed by a veterinarian. There are two methods commonly employed, both involve use of medication alongside physical therapy. The first involves gentle traction and torsion, the second involves distension of the uterus with fluid. Forced extraction of the membranes is never indicated. Membranes that cannot be removed easily using any of the above methods may need to be left in situ and the mare treated aggressively with medication.

Following removal of retained membranes, it is vital that the mare’s uterus is flushed to aid in removal of debris, to reduce the bacterial load and to stimulate uterine contractions. Systemic treatment with antibiotics and anti-endotoxic therapy is also indicated. Follow up examination is warranted to check that metritis has not developed.

The mare’s prognosis for reproductive performance is not affected by the incidence of retained foetal membranes, assuming appropriate management has occurred.


Metritis is a relatively uncommon event post foaling, but increases with birth trauma and retained foetal membranes. Mares usually present within 2-4 days of foaling. Inflammation of the uterus permits bacteria and toxins to enter the systemic circulation. Any recently foaled mare with a fever, and loss of appetite, with or without signs of laminitis, should be suspected of having metritis. A large volume of toxic, red-brown watery fluid may be present in the uterus before any obvious discharge becomes apparent.

Affected mares require treatment with broad spectrum antibiotics, anti-inflammatory drugs and potentially fluids. Oxytocin therapy is also indicated. Daily or twice daily flushing of the uterus constitutes part of the routine management of mares with metritis. It should be repeated until the returning fluid is free of grossly visible contamination. If the mare presents with additional signs of laminitis, then this will need additional management with frog supports, analgesia and confinement on deep, soft bedding.