You can check for signs of pregnancy in your mare at home by observing her behavior around a stallion, watching for physical changes over time, and using commercially available hormone test kits. None of these methods match the accuracy of a veterinary ultrasound, but together they can give you a reasonable idea of whether your mare has conceived. Horse pregnancy lasts about 340 days on average, with a normal range of 320 to 360 days, so the signs you look for depend heavily on how far along she might be.
Teasing With a Stallion: The Earliest Home Test
The simplest early indicator is how your mare responds to a stallion or teaser. A mare in heat will show interest, raise her tail, squat, and urinate. A pregnant mare does the opposite. From about day 12 to day 24 after breeding, daily teasing should show aggressive rejection of the male if she has conceived. She may pin her ears, kick, squeal, or strike out rather than standing receptively.
This method has real limitations. Some mares are naturally standoffish around stallions whether pregnant or not, and others can show what’s called “silent heat,” where they cycle without obvious signs. A mare that rejects a stallion isn’t guaranteed pregnant, and one that seems mildly interested isn’t guaranteed open. Still, consistent aggressive rejection across multiple teasing sessions is a meaningful early clue, especially if her behavior before breeding was clearly different.
Belly and Body Changes Through Pregnancy
Physical changes are the most intuitive thing to watch for, but they take time to appear and vary a lot between mares. A first-time mother may not show obvious belly growth until well into her pregnancy, while a mare who has foaled before can look noticeably rounder much sooner. By about five months, many mares have changed shape enough that their regular saddle no longer fits properly. That expanding barrel is one of the more reliable visual cues in mid-pregnancy.
About a month before foaling, many mares develop noticeable swelling along the lower abdomen. The udder begins slowly enlarging around the same time and grows rapidly in the final two weeks. During early development, the udder stays firm. A few days before birth, it softens and fills with fluid that gradually shifts from thin and watery to thick colostrum. One to two days before delivery, colostrum is present. Small dried wicks of mammary secretion, often called “waxing,” typically appear about one day before foaling, and in the final hours some mares drip milk.
The pelvic ligaments on either side of the tail head also soften as foaling approaches, making the tail head look more elevated or prominent. These late-stage signs are useful for predicting when foaling will happen rather than confirming pregnancy itself. If you’re trying to determine pregnancy in the first few months, physical appearance alone won’t tell you much.
Watching for Fetal Movement
Later in gestation, you can sometimes see the foal moving by watching your mare’s flank. This is most visible when the mare is standing quietly, and the movement looks like a ripple or bump along her side. A veterinarian using rectal palpation can detect fetal movement (through a technique called ballottement) between 90 and 120 days, but visible movement from the outside typically doesn’t become obvious until much later in pregnancy. If you can see the foal shifting from several feet away, your mare is well into her second half of gestation. Keep in mind that fetuses can be quiet for long stretches, so not seeing movement on any given day doesn’t mean something is wrong.
Home Hormone Test Kits
Commercially available test kits can detect a hormone called pregnant mare serum gonadotropin (sometimes abbreviated PMSG or called equine chorionic gonadotropin). These kits work on a blood sample and are designed for quick, on-farm results without sending anything to a lab. The hormone they detect rises in the mare’s blood starting around day 40 to 45 of pregnancy and peaks between days 60 and 80.
A separate hormone, estrone sulfate, offers another testing option. It’s produced by the placenta and can be detected in blood, urine, or milk after about day 50 of pregnancy. When tested any time after day 50, estrone sulfate assays have been reported to have nearly 100% accuracy for confirming pregnancy. However, most estrone sulfate testing requires sending a sample to a lab rather than using a simple on-farm kit.
For either type of test, timing matters. Testing too early will give you a false negative because the hormone levels haven’t risen high enough to detect. If you bred your mare and want to test at home, waiting until at least 45 to 50 days post-breeding gives you the best shot at a reliable result.
What Progesterone Levels Tell You
Progesterone is the hormone that maintains early pregnancy. A blood concentration of 4 nanograms per milliliter or higher is considered adequate to sustain the pregnancy during the first two to three months. If it drops below that threshold, the pregnancy is at risk. Some horse owners have their veterinarian run a progesterone blood test as a quick early check: high progesterone past the point where a non-pregnant mare would have cycled back into heat suggests she’s carrying.
This isn’t something you can do with a kit at home, but it’s worth understanding because progesterone monitoring is one of the most common early pregnancy tools your vet might recommend. A single high reading doesn’t confirm pregnancy on its own, since other conditions can keep progesterone elevated, but a pattern of sustained high levels combined with stallion rejection is a strong signal.
Why Home Methods Have Real Limits
The core problem with relying entirely on home detection is that the most common signs of pregnancy, like a growing belly or behavior changes, are subjective and can be mimicked by other conditions. A mare that stops cycling might have a hormonal issue rather than a pregnancy. Abdominal expansion can come from weight gain, fluid accumulation, or digestive changes. Silent heat and pseudopregnancy are common reasons for false pregnancy conclusions.
More critically, home methods cannot detect twin pregnancies. Twins in horses are dangerous. Most equine twins don’t survive to term, and those that do frequently result in weak or nonviable foals and serious complications for the mare. An ultrasound performed by a veterinarian between days 14 and 16 can identify twins early enough to manage the situation, often by reducing one embryo to give the other a healthy chance. No behavioral observation or hormone kit will tell you whether your mare is carrying one embryo or two.
Home methods also can’t distinguish pregnancy from uterine infections or other reproductive conditions that may produce similar signs. A mare with a uterine fluid accumulation might reject a stallion and test positive on certain hormone assays while not actually carrying a viable pregnancy.
A Practical Home Monitoring Timeline
If you’ve bred your mare and want to track things at home, here’s a rough schedule of what to watch for:
- Days 12 to 24: Begin daily teasing with a stallion. Consistent aggressive rejection is your first clue.
- Days 45 to 50: Home test kits for pregnant mare serum gonadotropin become usable. Estrone sulfate lab tests also become reliable around day 50.
- Months 3 to 5: Gradual belly enlargement may become noticeable, especially in mares that have foaled before.
- Month 10 (about 30 days before foaling): Abdominal swelling drops lower. Udder begins developing.
- Final 2 weeks: Udder grows rapidly. Pelvic ligaments soften. Tail head looks more prominent.
- Final 1 to 2 days: Colostrum present. Waxing appears on teats. Some mares drip milk in the last hours.
The wide normal range for gestation, anywhere from 320 to 360 days with some healthy foals born as late as 388 days, means there’s no single “due date” to count on. This makes late pregnancy monitoring especially important. A mare at 350 days with no udder development is likely just running long, but one at 330 days with waxing and softened ligaments could foal any time.