How to Tell if Your Mare is Pregnant and Why It's Important

If you're wondering if your mare may be pregnant, there are a few ways to figure it out. The gestation period of a female horse is approximately eleven months. For the first few months, there may be no visible signs that the mare is carrying a foal. If you suspect your mare is in foal, it is essential that she is cared for properly right from the beginning of her pregnancy, to optimize both her health and the health of the foal.

How to Tell If Your Mare is In Foal and Why It's Important

The only way to be sure that your mare is in foal and that the pregnancy is progressing normally is to have your mare examined by a veterinarian, preferably one who specializes in equine reproduction. This should be done about 14 to 18 days after the mare has been bred.

At this point, the veterinarian can determine if the mare is carrying twins. Twin pregnancies are a major cause of re-absorption and spontaneous abortions in horses. If your mare is carrying twins, one of the embryos can be 'pinched off,' to give the other embryo a better chance for normal development. It may seem cruel, but the benefits must be weighed alongside the risks. The chances of a mare surviving the birth herself and successfully producing strong twin foals are slim. Neither the mare nor the twins may survive, if both embryos are allowed to develop.

The mare should be checked again at regular intervals as determined by the vet, to ensure that she's still in foal and there are no uterine infections that need attention. As the vet can confirm whether the pregnancy is progressing normally and how advanced it may be, you should know at a fairly early stage whether there might be any complications.

Care and Feeding for Pregnant Mares

You would want to determine early on whether your mare is in foal, because her feeding and management may require slight adjustments. You will need to ensure your mare has the best-quality hay or pasture, salt, and minerals. If your pasture grass contains fescue, you may want to remove the mare and allow her to graze elsewhere. You may want to separate your mare from any pasture bullies that could cause her harm or injury, and thus make the foaling process more difficult for her.

While it's important to maintain a regular vaccination and deworming schedule throughout the pregnancy, your mare shouldn't receive these medications during the first two to three months. Some vaccines and parasite control medications can interfere with fetal development. Your veterinarian is the best resource for advice about which medications are safe to give your pregnant mare throughout her pregnancy.

Yes, it costs money to have your mare properly examined by a veterinarian, but the cost is negligible in comparison to the total cost of raising a foal—or losing a foal or the mare. Breeding a mare is not a cheap way of getting another horse. In fact, raising a foal can be one of the more expensive ways of producing another horse!

Improper Assumptions About Pregnancy in Mares

• Sometimes people feel that nature will take care of things. This doesn't always lead to the best outcome. With proper care early in the pregnancy, potential health problems that could affect the reproductive health of your mare, and the health and life of the foal can be prevented.
• There are several folk methods and theories to determine whether your mare is carrying a foal or not. But these methods are neither reliable nor accurate.
• The lack or presence of a heat (estrus) cycle is not a sure indicator of pregnancy either. Some mares will appear to have a heat cycle despite being in foal, because of increased estrogen levels. Other mares may show no obvious signs of a heat cycle, especially during the fall and winter months.
• Pregnancy is impossible to determine early on, simply by looking at the mare. Some mares, especially those that have not carried a foal before, may not 'show' much at all. Others have a well-sprung barrel that looks like they are in foal all the time. This can be because they’ve had several foals before, or it may be because the mare has a hay belly that makes her abdomen look distended.
• Not all mares show obvious signs of being in foal, even late in the pregnancy. While some mares may look fuller and their udders may appear to be full of milk for a few weeks before foaling, others may not. Some will show very evident signs that they are in foal, or about to foal. There have been situations in which an owner had no idea that the mare was in foal, until the foal arrived.