Abortion in Mares: Immediate Care, Causes and Protecting Other Horses
In diesem Artikel
By Dr Duncan Houston
Losing a pregnancy is distressing, especially when the mare looked well beforehand. The first priorities are her safety, protecting other horses and preserving the information that may explain what happened.
A mare can abort without obvious warning. Even if she seems comfortable afterwards, veterinary assessment is still important.
Quick Answer
Call your equine vet promptly after suspected abortion and separate the mare from other horses, particularly pregnant mares. Treat the fetus, placenta and fluids as potentially infectious until advised otherwise. Severe pain, heavy bleeding, weakness, difficult delivery or retained placenta need urgent veterinary attention.
What signs can precede pregnancy loss?
Unexpected vaginal discharge, premature udder development or milk production, abdominal discomfort and fever can warrant investigation. These signs do not establish that the pregnancy will be lost, but they should not be watched passively until the next routine appointment.
Gestation dates help the vet interpret what has happened, but a foal delivered early and showing signs of life also needs urgent neonatal care. Do not decide that treatment is futile solely from a calendar estimate.
Why do mares abort?
Causes include placental infection, equine herpesvirus, leptospirosis, other regionally important infections, twins, umbilical-cord problems and fetal abnormalities. Some losses remain unexplained despite good testing. Leptospirosis is bacterial, not viral.
The MSD review of equine abortion distinguishes infectious and non-infectious causes. The appearance of the fetus or whether the mare was vaccinated cannot reliably rule infection in or out.
Twins are an important preventable risk identified through early pregnancy examinations. Pasture-associated risks differ by region, so management advice for one country should not automatically be applied everywhere.
How urgent is the situation?
| Situation | Next step |
|---|---|
| New discharge or early milk development during pregnancy | Call your vet the same day. |
| Pregnancy loss, mare currently standing and comfortable | Contact your vet promptly, isolate and preserve tissues. |
| Severe pain, heavy bleeding, collapse or a foal stuck during delivery | Emergency veterinary attendance. |
| Placenta not passed within three hours of delivery | Urgent veterinary assessment; call earlier if the mare is unwell. |
When is this an emergency?
Call immediately for difficult delivery, significant bleeding, weakness, severe colic or fever with depression. Retained membranes can lead to serious illness. The Merck guidance on retained placenta identifies three hours as the usual threshold after delivery. Do not pull on attached membranes.
If a red, velvety membrane appears during delivery, call for immediate veterinary guidance: premature placental separation can cut off the foal’s oxygen supply. Do not spend time searching online while delivery is obstructed or progressing abnormally.
What should you do right now?
- Call your vet with pregnancy dates, time of events, mare’s condition and whether the placenta has passed.
- Keep the mare apart from other horses and restrict access to the contaminated area.
- Wear gloves and suitable protective clothing. Keep children, pregnant people and immunocompromised people away from tissues and fluids.
- Preserve the entire placenta and fetus if possible, following your vet’s instructions for safe packaging and cooling. Do not wash, cut up or discard them.
- Use separate equipment and footwear, and ask about cleaning, disinfection and monitoring exposed horses.
The AAEP infectious-abortion diagnostic guidance emphasises systematic examination and appropriate sampling. Your vet or laboratory should direct sample handling; owners should not add chemicals or attempt a post-mortem examination.
What treatment and follow-up may be needed?
The vet assesses the reproductive tract, placenta completeness, hydration and systemic health. Treatment depends on the findings and may address retained tissues, infection, pain or fluid deficits. Not every loss needs the same medication, and antibiotics do not prevent every cause.
Ask for a written plan for the mare, contact horses and future breeding. Test results may change isolation or management advice. Rebreeding should wait until recovery and reproductive assessment support it.
Common mistakes
- Discarding the placenta because the mare looks well.
- Pulling retained membranes out by force.
- Allowing other horses to investigate the fetus or fluids.
- Assuming vaccination excludes an infectious cause.
- Breeding again before the cause and recovery have been reviewed.
Reducing future losses
Plan early ultrasound for twins, appropriate pregnancy monitoring and locally suitable vaccination with your vet. Separate pregnant mares from travelling horses where practical. Maintain good nutrition, pasture safety and breeding hygiene. Vaccination reduces particular risks but does not replace biosecurity or guarantee a live foal.
Frequently asked questions
Can a mare abort and still look healthy?
Yes. Her appearance does not exclude infection or retained membranes.
Should I keep the fetus and placenta?
Yes, with safe handling and veterinary instructions. Both can be important diagnostically.
Can other mares be at risk?
Yes if the cause is infectious. Separate and seek a herd plan until assessed.
Can the mare have another healthy pregnancy?
Often this is possible, but outlook depends on the cause and her recovery.
Prompt care and sensible biosecurity protect the mare while giving you the best chance of understanding the loss.
For help understanding your horse’s care and preparing questions for your veterinarian, visit ASK A VET™. Urgent signs need an equine veterinarian in person.
