Pet Keen is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Home > Horses > How to Tell If a Horse is Pregnant: 4 Signs to Look For

How to Tell If a Horse is Pregnant: 4 Signs to Look For

pregnant horse

Just like other animals, horses often show many signs that they’re pregnant. Often, it is harder to notice their pregnancy in the beginning. However, as the pregnancy continues, it often becomes easier and easier to tell that the mare is pregnant.

If you’re interested in whether or not your mare is pregnant, there are many signs you can look for. However, not all horses show obvious signs of pregnancy. In many cases, you’ll need to consult with a veterinarian to determine if your horse is pregnant or not.

Furthermore, you’ll need to get your horse regular vet care while she is pregnant.

PetKeen_How to Tell If a Horse is Pregnant_Infographic_v3_Apr 24 2023-01
You’re welcome to use our images, but we require you link directly to this site for credit (ex. Image from Pet Keen)

new horse shoe divider

The 4 Signs That Tell You a Horse Is Pregnant

1. Physical Changes

Many females exhibit at least some physical changes when they are pregnant, especially as the pregnancy matures. Some of these are pretty obvious, while others may be harder to notice. Often, keeping an eye on your horse for any apparent changes is the best way to pick up on these differences.

  • Enlarged stomach. As you’d probably guess, a mare’s stomach will grow as the foal grows. The mare’s stomach should gradually increase in size throughout pregnancy. However, it is most noticeable at the end of pregnancy. The mare’s belly often appears rounder. The muscles on either side of the spine may become more relaxed.
  • Nipple development. In preparation for feeding the foal, a mare’s nipples will become larger and more prominent. Often, this doesn’t occur until the last month of pregnancy, though. They may also become softer and more pliable.
  • Udder development. The mare’s udder may go through some changes, too. It may swell and become firm as the mammary glands begin to produce milk. Blood flow will increase to the area, causing the udders to feel slightly warmer than the rest of the body.
  • Tailhead relaxation. The muscles at the base of the mare’s tail become looser as the pregnancy progresses. This difference is due to hormones that prepare the mare’s body for delivery.
  • Fetal movement. In the later part of the pregnancy, you may notice signs of discomfort as the foal moves about in the mare’s womb. The horse may randomly flinch or change positions often. Pregnancy can be very uncomfortable, especially in the later stages.

Most of these changes occur during the latter part of pregnancy—with practically none occurring at the beginning. Therefore, it’s often a while before you notice pregnancy if you’re basing it on physical changes only.

closeup portrait of a pregnant horse
Image By: Daniel Sockwell, Shutterstock

2. Behavioral Changes

Mares often experience several behavioral changes throughout pregnancy, as well. These vary a lot from horse to horse. Some may pop up and be quite obvious for a few days before disappearing completely. Others may never show up at all, or they may appear at the beginning of the pregnancy and then never leave.

  • Changes in appetite. Pregnant horses often experience some appetite changes, though the exact details vary. Some eat more. Others eat less. Some mares may have cravings for specific foods. It isn’t uncommon for them to completely turn down a food they once loved, either.
  • Changes in energy levels. Mares often become more tired when they’re pregnant. They’re developing a foal, and that often requires a lot of energy. However, others may become more active.
  • Horses don’t build literal nests. However, you may notice the female looking for a suitable spot to give birth once she reaches the end of her pregnancy. She may rearrange bedding and dig at the ground, for instance.
  • Many mares seem more aggressive or irritable during pregnancy. In many cases, this may be due to discomfort. However, mares also have changes in hormones, which can cause aggression.
  • Separation Anxiety. Many mares may become extra-attached to their herd or human caregivers while pregnant. In all likelihood, this is due to hormonal changes.

Not all females experience these changes. Every horse and pregnancy is unique. However, these changes can help indicate that your mare is pregnant.

man comforting a horse in stable
Image By: michaeljung, shutterstock

3. Ultrasound

An ultrasound is a noninvasive way for a veterinarian to confirm pregnancy. It’s used for a wide range of different animals, including horses. Ultrasounds can also be utilized to detect abnormalities in the fetus and measure its size.

During an ultrasound, a special gel is applied to the mare’s stomach area and a handheld device is utilized to transmit high-frequency sound waves. These bounce off tissue they come into contact with, which the device detects. In this way, it can create a view of the fetus and surrounding structures.

Ultrasounds can be performed fairly early effectively, sometimes as early as 14 days after ovulation. The pregnancy can be confirmed by looking for a small structure called a gestational sac that develops very early in pregnancy.

Ultrasounds can also be utilized to monitor the pregnancy as it develops. Because it’s noninvasive and rather simple to perform, it may be done several times throughout the mare’s pregnancy to ensure that everything is developing properly. It allows complications to be picked up early.

Vet examining horse
Image By: mariait, Shutterstock

4. Bloodwork

Bloodwork can also be done to confirm pregnancy in mares. Specific hormones and proteins found in the blood only occur (or occur at raised levels) when the mare is pregnant.

One specific hormone that they measure during these blood tests is the equine chorionic gonadotropin. This hormone is produced by the placenta, so it is only around during pregnancy. Levels in the mare’s blood raise rapidly in the first few weeks of pregnancy, allowing blood tests to be utilized rather early.

Progesterone can also be measured to determine pregnancy. This hormone is around for most of the time throughout a mare’s life, but its levels raise substantially during pregnancy. It’s one of the hormones that helps the mare stay pregnant. Monitoring the levels of this hormone can help detect complications early, as well.

Equine bloodwork may also look for specific proteins, like pregnancy-associated glycoproteins. As the name suggests, these proteins are associated with pregnancy and can be detected as early as 40 days after ovulation. Therefore, they are another indicator that the mare is pregnant.

Along with ultrasounds, bloodwork plays another key role in determining if a mare is pregnant.

Vet takes blood from a Friesian horse from the neck vein with vacutainer blood tubes
Image By: Henk Vrieselaar, Shutterstock



Physical signs of pregnancy don’t occur in horses until later in pregnancy. Therefore, they are often not an accurate way to determine if a mare is pregnant or not. The mare should be receiving extra supportive care long before physical signs may develop. Therefore, it’s important to use diagnostic methods to determine if a mare is pregnant.

These diagnostic methods are bloodwork and ultrasounds. Both of these tests can determine that a horse is pregnant rather early, and they can help ensure the pregnancy is developing properly.

Featured Image Credit: Marie Charouzova, Shutterstock

Our vets

Want to talk to a vet online?

Whether you have concerns about your dog, cat, or other pet, trained vets have the answers!

Our vets