Pregnant Mare Signs

Pregnant mares show few external signs that they are pregnant. If you are running a breeding farm, discovering that a mare isn't pregnant until late in the year can result in lost earnings. Working with a veterinarian, especially a reproductive specialist, will give you the best results.

  1. Heat

    • Some people believe if their mare does not go into heat again after being bred, she is pregnant. However, many mares do not exhibit regular heat cycles, and some mares exhibit "silent heat," where they are ovulating but do not act like they are. Of course, if you know your mare's heat cycles well, not going into heat may be an indicator. She should be teased by a stallion for up to 40 days, though, to prove she is not going to go into heat.

    Ultrasound

    • The better option, however, is to order an ultrasound for your mare. A vet can do this with 95 percent accuracy in as early as 14 days after the breeding. You should have an ultrasound performed again at 40 days after breeding to be certain your mare is still in foal.

    Palpation

    • Before ultrasound technology, rectal palpation at or after 18 days was the only way your veterinarian would have been able to tell your mare was pregnant, and veterinarians without ultrasound machines still check for pregnancy by palpation. Some older breeders were able to palpate their mares themselves. Accuracy of palpation depends on the skill of the person doing the palpation. The Horse Owner's Veterinary Handbook says the person palpating would be looking for firm uterine horn and cervix (the cervix also should be contracted). However, this is something a novice should not attempt, as you can easily damage your mare's reproductive organs.

    Pregnancy Test

    • There is a pregnancy test for mares, called the mare immunological pregnancy test. The mare's blood serum is tested 40 days after breeding for the hormone equine chorionic gonadotropin. This test is accurate 95 percent of the time, but it can produce a false positive if the mare lost her foal after the 37th day.

    Other Tests

    • Your mare's blood plasma and milk, if she is lactating, can also be tested for elevated progesterone levels, which mean pregnancy. These tests can be performed after the 16th day of gestation, but they are only 90 percent accurate.