Retained Placenta in a Mare: Symptoms, Risks & When to Call the Vet
- In mares, the placenta should usually pass within 3 hours after foaling. After that, retained fetal membranes are treated as an emergency.
- Major risks include uterine infection (metritis), endotoxemia, laminitis, reduced milk production, and in severe cases death.
- Do not pull on the hanging placenta. Keep it from dragging or being stepped on, and call your vet right away.
- Your vet may use oxytocin, anti-inflammatory medication, antibiotics, uterine lavage, and monitoring for toxemia or laminitis.
- Fast treatment often leads to a good outcome, especially before the mare develops fever, depression, or hoof pain.
Common Causes of Retained Placenta in a Mare
Retained placenta means the mare has not completely passed the fetal membranes after foaling. In horses, this is usually considered abnormal once 3 hours have passed. The problem is often not something a pet parent caused. It can happen even with attentive foaling management.
Common risk factors include dystocia, difficult or assisted delivery, twins, abortion, stillbirth, placentitis, uterine fatigue, and trauma to the reproductive tract. Mares that needed significant manipulation during foaling are often treated more aggressively because the risk of infection and delayed membrane release is higher.
Sometimes only a small piece is retained, especially the tip of the nonpregnant horn. That means a mare may appear to have passed most of the placenta but still have dangerous tissue left behind. This is one reason your vet may want the placenta saved and laid out for inspection.
Breed and individual factors may also matter. Some equine reproduction references note that draft-type mares and mares with postpartum metabolic issues can be at higher risk in some situations, but any mare can develop retained fetal membranes.
When to See the Vet vs. Monitor at Home
See your vet immediately if the placenta has not passed within 3 hours after the foal is born. This is not a wait-and-see problem in mares. Early treatment can reduce the risk of metritis, endotoxemia, and laminitis.
Call even sooner if your mare has a fever, seems depressed, stops eating, shows colic signs, has a foul-smelling or bloody discharge, is reluctant to move, or develops hot feet or a strong digital pulse. Those signs can mean infection, systemic inflammation, or early laminitis.
Home monitoring is limited to supportive observation while you are waiting for your vet. You can keep the hanging membranes clean and off the ground by tying them in a loose knot above the hocks if needed, but do not add weight and do not pull. Save the placenta for examination if it passes before your vet arrives.
If you are unsure whether the placenta is complete, treat that uncertainty as urgent. A mare can retain only a small portion and still become very sick.
What Your Vet Will Do
Your vet will start with a postpartum exam, temperature check, heart rate assessment, and evaluation of the uterus and placenta. They may inspect the passed membranes to see whether both horns are present and whether a tip may still be missing. If the placenta is still attached, they will assess how much remains and whether the mare is already showing signs of toxemia or laminitis.
Early treatment often includes low-dose oxytocin to stimulate uterine contractions and help expel the membranes. Depending on the case, your vet may repeat doses over time. If the membranes have been retained longer, or if the mare is ill, treatment often expands to anti-inflammatory medication, broad-spectrum antibiotics, fluids, and close monitoring.
Some mares also need uterine lavage or other reproductive procedures to help remove debris and reduce contamination. Your vet may recommend bloodwork, ultrasound, or referral if the mare is systemically sick, painful, or not responding as expected.
Because laminitis is one of the most feared complications, your vet may also monitor digital pulses, hoof heat, stance, and comfort very closely during the first day or two after treatment.
Treatment Options
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Urgent farm-call exam
- Post-foaling reproductive exam
- Low-dose oxytocin injections
- Basic anti-inflammatory treatment if indicated
- Placenta inspection and short-term monitoring instructions
Recommended Standard Treatment
- Urgent exam and repeated reassessment
- Oxytocin protocol
- NSAID therapy such as flunixin if your vet recommends it
- Broad-spectrum antibiotics when retention is prolonged or infection risk is higher
- Uterine lavage or assisted reproductive management as indicated
- Monitoring for metritis, endotoxemia, and laminitis
Advanced / Critical Care
- Equine hospital admission or intensive on-farm critical care
- IV fluids and aggressive endotoxemia support
- Serial bloodwork and ultrasound
- Advanced uterine treatment and repeated lavage if needed
- Laminitis prevention and hoof support
- Referral-level monitoring for systemic illness or severe pain
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Retained Placenta in a Mare
Bring these questions to your vet appointment to get the most out of your visit.
- Has my mare retained the entire placenta or only a piece?
- Do you recommend oxytocin now, and how soon should we expect a response?
- Does my mare need antibiotics or anti-inflammatory medication based on how long the placenta has been retained?
- Are there signs of metritis, endotoxemia, or early laminitis right now?
- Should we save and examine the placenta, and what should a complete placenta look like?
- What changes in temperature, appetite, discharge, or hoof comfort mean I should call back right away?
- Does my mare need bloodwork, ultrasound, or referral to an equine hospital?
- How should I monitor the foal and nursing while my mare is being treated?
Home Care & Comfort Measures
Home care does not replace veterinary treatment for a retained placenta. While waiting for your vet, keep the mare in a clean, quiet area with easy footing and fresh water. If membranes are hanging, keep them from dragging or being stepped on. A loose knot above the hocks can help shorten them, but do not pull on them and do not tie on weights.
Watch your mare closely for fever, depression, reduced appetite, colic signs, foul discharge, stiffness, or reluctance to walk. Check whether the foal is nursing normally, because a sick mare may be less attentive or may produce less milk. Save any passed placenta in a clean bag or bucket for your vet to inspect.
After treatment, follow your vet's instructions exactly. That may include taking the mare's temperature, checking digital pulses, limiting stress, giving prescribed medications, and watching for laminitis warning signs such as hot feet, shifting weight, or a rocked-back stance.
If your mare seems worse at any point, call your vet again the same day. Retained placenta cases can change quickly, and early recheck care can make a major difference.