What is Retained Fetal Membranes (Mares)?
Most mares will fully expel all fetal membranes within three hours after giving birth. There are some instances where the expulsion of the fetal membranes is delayed for 8 to 12 hours without the mare being in distress or becoming ill. There are times when your mare is unable to fully expel the fetal membranes, the retention can cause your mare to become very ill and in some cases is fatal.
After your mare births her foal, you will need to watch for the afterbirth, or fetal membranes, to present. If you do not see them be expelled within several hours or you notice that your mare is in distress, contact your veterinarian. Metritis, an infection of the uterine wall, along with endotoxemia, a bacterial infection, can develop if the fetal membranes are not fully expelled from the uterus.
Fetal membranes are the membranes that surround a developing fetus. There are two membranes, amnion and chorion, that make up the amniotic sac. The amniotic sac protects the fetus. There is also the allantois membrane and the umbilical vesicle. All of these membranes must be fully expelled from your mare following delivery of the foal.
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Symptoms of Retained Fetal Membranes (Mares) in Horses
In some cases, the entire placenta and all fetal membranes are not expelled, while in other cases, there are only pieces of the fetal membranes that remain in the uterus. Either way, problems can arise for your mare if all fetal membranes are not removed after delivery. Be sure to thoroughly examine the placenta that is expelled, looking for any tears or missing pieces that might still be retained in your mare. Contact your veterinarian if you are unsure that all fetal membranes have been fully expelled.
- Only part of the placenta is expelled
- Pieces missing from the expelled placenta
- Fetal membranes visibly hanging out of the vulva
- No placenta is expelled
- Agitated behavior
- Acting as if still in labor
- Abnormal mucus membrane color
- Muscle twitching
- Abnormal manure production
Causes of Retained Fetal Membranes (Mares) in Horses
The cause of retained fetal membranes is not exactly known. Researchers lean more towards a hormonal imbalance that causes the uterus to not contract enough after the foal is born to expel the fetal membranes. Postpartum contractions of the uterus occur when the levels of oxytocin are normal. When the hormone level of oxytocin drops, abnormal uterine contractions can occur, causing the mare to be unable to fully expel all fetal membranes.
Diagnosis of Retained Fetal Membranes (Mares) in Horses
It can be visually obvious in some cases that the mare has retained fetal membranes. The lack of the placenta being expelled or having the placenta protruding from the vulva are good signs that the fetal membranes have not been fully expelled. When there are pieces of fetal membrane retained inside the uterus, it can be more difficult to diagnose the problem.
Your veterinarian will fully examine your mare and all fetal membranes that have been expelled. A rectal examination will be performed so your veterinarian can palpate the uterus and feel for any abnormal matter still within. A transrectal ultrasonograph may be used to evaluate the uterus.
Treatment of Retained Fetal Membranes (Mares) in Horses
If the placenta is present, but still hanging from your mare’s vulva, your veterinarian will tie it up to keep it from touching the hocks and causing more distress for your mare. Your veterinarian will conduct a full physical and monitor any contractions that your mare may still be experiencing.
An injection of oxytocin will be recommended. The injection should only be given up to six hours after delivery of the foal. This injection will raise the levels of oxytocin within your mare and allow her uterus to contract strong enough to push the fetal membranes from your mare’s body. Oxytocin is injected intramuscular and can be repeated one hour after the initial injection if all the fetal membranes have not been passed.
Manual removal of the fetal membranes should be done only if the oxytocin injections do not produce the desired results. This procedure should be done using extreme caution. The slightest bit of force can cause your mare’s uterus to become inverted or prolapsed. Hemorrhaging can also be a concern when trying to manual removing fetal membranes.
Your veterinarian will prescribe a broad spectrum antibiotic for your mare even after all fetal membranes have been removed. This is to ensure that no infection can set in and cause severe complications for your mare.
Recovery of Retained Fetal Membranes (Mares) in Horses
Immediate treatment for retained fetal membranes will give your mare the best chance of a full recovery. Many mares have suffered from this condition but have been able to go on to birth other foals with no problem. Your veterinarian will be able to tell you the prognosis for your mare once they remove all the fetal membranes.
Your mare will need to have regular examinations to check that the uterus does not retain any lasting effects from retaining fetal membranes. If you are planning to breed your mare again, regular checks throughout her pregnancy may be advised by your veterinarian.