Signs A Horse Might Be Pregnant

Last Updated on February 5, 2022

Who doesn’t love foals? As cute as they are, bringing them into this world and dealing with pregnant mares can be a hassle.  But, how to tell if a horse is pregnant? A mare’s pregnancy can be 2-3 months longer than a human’s, and they can be just as grumpy!

When working with breeding horses, it is important to be able to predict when horses will breed when you can tell a mare is pregnant, what signs you should look for to see if a mare is pregnant, and what to do for your mare if you determine that she is pregnant.

I will be talking about all of these things and more in this article.  Dealing with pregnant mares for the first time, or curious as to how the process goes down? Continue reading, and be prepared that this process isn’t nearly as cute as the end result!

When Do Horses Breed?

Like many other types of animals, horses tend to breed at certain times of the year.  A mare’s gestation period can be anywhere from 11-12 months- Mares carry their foals for almost an entire year! 

How Long Is A Horse Pregnant?

That’s 2-3 months longer than a human’s gestation period, so almost another trimester! Mares that have foaled before will sometimes carry for a shorter time period than mares who are carrying their first foal.  But, as with everything, it will depend on the horse.

When Do Horses Breed?

Horses instinctively want their foals to be born into warm, springtime weather so that they will be warm and have access to green pasture.  So, horses tend to want to breed around the springtime or summertime, in order for this to happen.  

But, horse breeders have figured out how to manipulate this natural process in order to have foals at their preferred times of the year.  They often even use artificial lighting in order to trick the mare’s brain into producing reproductive hormones that are typically activated by the sunlight of spring or summer time.

Find out What Time Of Day Do Horses Give Birth?

When Can You Tell if a Horse is Pregnant?

As with people and other animals, sometimes you don’t know if your mare is pregnant or not for some time after she may have conceived.  The biggest hint for the first three months may be that she will not go into heat. 

Outside of that, you may not be able to tell until after the first three months or her pregnancy has passed. Your mare will not begin to “show” (in other words, be visibly pregnant around her barrel) until she is about six months pregnant.

How To Tell If A Horse Is Pregnant?

Transrectal Ultrasonography

There are many ways you can tell if your mare is pregnant.  Some are old wives’ tales, and some have a scientific value. One of the most reliable scientific methods of telling if your mare is pregnant is transrectal ultrasonography.


Transrectal ultrasonography can detect your mare’s pregnancy ten or eleven days post-ovulation, so very early in her pregnancy.  It can also give you an estimated date of foaling if you’re unsure when the breeding occurred.

Best of all, transrectal ultrasonography can let you see the fetus and its heartbeat, so long as it has been viable for 25 days or more.

Blood Tests

Similar to humans, you can also tell if your mare is pregnant by blood tests. If your mare is pregnant, she will show elevated levels of progesterone in her blood.  However, this test isn’t foolproof, as sometimes even non-pregnant mares will have elevated levels of progesterone.

However, blood tests that show equine chorionic gonadotropin (eCG) are a direct positive indicator of a mare’s pregnancy.  But, this won’t be detectable until a little after the first month of a mare’s pregnancy.  

Behavioral Signs

While less certain than scientific tests, your mare will often show behavioral signs that she is pregnant, even from an early stage.  The biggest of these is disinterest in geldings or stallions.

Traditionally, mares get moody or “flirty” around male horses.  If your mare is not showing the same emotions around male horses as she typically does, there’s a good chance that she might be pregnant.

There’s also an old wife’s tale that, when a mare is pregnant, she will only shake her head and neck as opposed to her whole body, in order to protect her unborn foal.  But, this has never been backed up by scientific proof.

What Should You Do if a Mare is Pregnant?

The most important thing to do while your mare is pregnant is to have regular checkups for both her and her foal and to follow whatever instructions your vet may have for you.  Sometimes your horse’s diet will need to be adjusted, and sometimes their turnout will need to be adjusted.

There will be different things that can be done to help each individual horse, depending on their circumstances.  But, keeping in regular communication with a vet that has experience foaling mares will help you know how to best care for your pregnant mare.

When she begins showing signs that she is going to foal, you need to make sure you have a comfortable, big, bedded area in which she can go.  And again, as always, immediately call your vet.

What Should You Do if a Mare is Pregnant?


Having a pregnant mare can be challenging and tiresome, but the result will be well worth it! It is important to make sure you can detect your mare’s pregnancy early on, in order to get her checked by a vet as soon as possible, and thereby know how best to keep her comfortable.

There are both scientific ways and natural ways to know if your mare is pregnant- whichever you decide to follow, make sure you are careful and keep your horse’s best interests in mind.  In other words, make sure you are doing what is best for your mare.

I hope this article helped you learn how to tell if your horse is pregnant, and what to do about it. If so, please share this article, and share with us your experiences dealing with pregnant mares and foals!

Which method is used to evaluate a mare when she becomes pregnant?

In situations such as early pregnancy diagnosis, early confirmation of nonpregnant mares, and detection of more than one blastocyst within a mare, transrectal ultrasonography was considered the best way to detect pregnancy. However, recently, several alternative methods have been developed that allow the detection of pregnancy at an earlier stage than is possible with transrectal ultrasonography. These methods include measurement of progesterone in serum and urine, measuring circulating estradiol concentrations, and determining the presence of a corpus luteum on the ovary.

How many weeks are horses pregnant?

The pregnancy in mares in average takes about 338 to 343 days or up to 49 weeks. However, gestation can range anywhere from 320 to 380 days and it’s still considered normal. So you don’t have to worry to much if your mare is past due as long as she and her foal is healthy. 
Horses go through several changes during pregnancy, including increased appetite and weight gain. In addition to that they have to maintain the proper amount of body fat. If the mare doesn’t keep her weight in check, she may not be able to produce enough milk for her foal.

How much does it cost to check a horse for pregnancy?

After the mare is bred, a vet or equine veterinarian can perform a pregnancy check, which is a physical examination to detect pregnancy. A complete pregnancy check normally includes: a thorough examination of the mare, a blood sample, a urine sample, and a vaginal swab. The cost of the pregnancy examination ranges somewhere between $100 and $150. About 30 days after the pregnancy is confirmed another test should be done to confirm the heartbeat. The cost of this second test is very similar to pregnancy test which means that it will cost you around $200 to $300 in total. If the mare is pregnant, she should be examined regularly by the vet. 

How do I know if my horse is pregnant or just fat?

One of the first and most obvious signs of pregnancy in mare is the distended udder. This become even more obvious during the last month, when the udder usually enlarges. You might also notice changes in the size of the udder throughout a day as the udder normally fill up overnight while it appears smaller during the day. However, once you notice that the udder remains full throughout the day, the foaling is usually not far. The foaling starts with the contractions of the uterus. The contractions are strong enough to loosen the birth canal walls and make it possible for the foal to pass through the birth canal. 

How do you know when a horse is about to give birth?

The visual signs of a mare getting ready to give birth start weeks before the actual foaling. One of the first signs is the udder distension that begins 2 to 6 weeks prior to foaling. The relaxation of the muscles of the croup (tail head, buttocks, and lips of the vulva) normally starts 7 to 19 days prior to foaling. Closer to the date of foaling you will notice how the nipples fill up. This usually happens 4 to 6 days prior to foaling. And only 2 to 4 days before foaling the waxing of the teats starts. When the mare is about to give birth, her tail will arch up and over her back. This is most likely caused by a muscle spasm that is aggravated by the contractions of the birth canal.