Horse Side Vet Guide ®

Equine Health Resource

Pregnancy Loss, Mid-Term (6 Weeks to 6 Months)

Code Red - Call Your Vet Immediately, Even Outside Business Hours

Code Orange - Call Your Vet at Their First Available Office Hours

Code Red - Call Your Vet Immediately, Even Outside Business Hours

  • If the mare has also retained her placenta for longer than 3 hours.
  • If you have any doubt about the length of time your mare is taking to deliver.
  • A prompt vet examination of mare, fetus and placenta provides the best chance for a diagnosis.

Code Orange - Call Your Vet at Their First Available Office Hours

  • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.

Pregnancy loss is uncommon between 6 weeks to 6 months after conception. There are many cases in which pregnancy loss during this time frame will go undetected. Pregnancy loss during this time frame is usually due to twin pregnancies, viral abortion, or infections of the placenta.

Abortion is usually preceded by enlargement of the udder and some vaginal discharge. If a mare aborts, consider that she could have a contagious condition. Isolate her from others, and keep other horses away from aborted fetus, placenta and fluids.


For a mare that has aborted, assess the mare’s general health using the Whole Horse Exam (WHE). Pay particular attention to rectal temperature, and general attitude and appetite. Check the vulvar area for swelling or wounds. Assess the placenta as well as possible for completeness.

Monitor the mare’s behavior carefully for 24-48 hours. In some cases, a mare may deliver one twin fetus but still have a retained twin in the uterus.


Your mare’s general health and reproductive health should be evaluated by a vet. Your vet may suggest diagnostics to determine the cause of the abortion.

By identifying the cause, you and your vet may be able to limit future damage to your mare’s reproductive health, ensure fertility for rebreeding, or even protect other broodmares in the group (assuming the diagnosis relates to an environmental cause).

Aborted fetuses (and the placenta) are often eaten by scavengers before they are found, so just because you did not find a fetus does not mean that your mare did not abort. Red vaginal discharge in a supposedly pregnant mare may be all that you notice or see.

If possible, save the placenta and aborted fetus in a cool place for your vet to evaluate. Keep the mare isolated and fetal fluids away from your other horses until your vet has evaluated the situation.

Author: Doug Thal DVM Dipl. ABVP


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