How often do horses have twins?

Veterinarians will typically recommend removing one of the twin embryos to maximise survival and well-being of both mare and remaining foal

Nature does not favour the birth of equine twins, and many mares will abort within the first 40 days of pregnancy. Of the mares who carry twins longer than six weeks, 80% will abort during the eighth month of pregnancy. Aborting so late in the pregnancy can cause all sorts of complications for the mare, such as trauma, illness, infection and reduced fertility for the next breeding season. While it’s difficult to pinpoint exactly how often horses have twins, only one in 100 twin pregnancies goes all the way to full term. The reason is that the mare’s uterus is not designed to support two babies at once. If the mare does deliver one or two live foals, they are likely to have problems of their own. Twins are usually born prematurely, and are below average in size as their combined weight will total the weight of a normal, single foal. They rarely catch up to normal size and weight relative to the expectation. Veterinarians will typically recommend removing one of the twin embryos to maximise survival and well-being of both the mare and the remaining foal.

Twins are conceived as a result of the stallion’s sperm fertilising two eggs released when a mare double-ovulates. Thoroughbreds and Warmbloods are the most likely to have multiple ovulations of all the breeds, and therefore they tend to have twins more often than other breeds.

Over 101 of your equestrian questions answered in our Q&A special edition (HQ129) > Shop now