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For horse breeders and farm veterinarians, keeping a close eye on a mare’s pregnancy isn’t just about counting down the months — it’s about ensuring that the foal is growing healthy, safe, and strong. One of the most exciting (and relieving) moments during this time is hearing the foal’s heartbeat for the first time. Thanks to advancements in veterinary ultrasound, farms now have the ability to monitor fetal heart activity throughout pregnancy in real time, with more accuracy and less stress on the animals.
Let’s dive into how farms use ultrasound technology to observe the heartbeats of unborn foals — and why this tool is quickly becoming a staple in modern equine care.
Why Monitoring a Foal’s Heartbeat Matters
In the early stages of pregnancy, a mare may not show obvious signs. But by around day 25 to 30 post-ovulation, the fetal heartbeat becomes detectable using transrectal ultrasound. Detecting this heartbeat offers much more than just peace of mind. It tells us the embryo is viable, developing properly, and not undergoing early embryonic loss — a common risk in the first 60 days.
On large breeding farms, especially in regions like Kentucky, Australia, or parts of Europe where Thoroughbred racing is big business, early detection and follow-up heartbeat checks are essential. A weak or absent heartbeat is one of the first indicators that something may be wrong. Conversely, a strong and regular heartbeat reassures breeders and allows them to adjust management practices confidently.
What Kind of Ultrasound Is Used on Horses?
Veterinarians typically use a rectal probe (5-7.5 MHz linear transducer) for most equine pregnancy checks. This allows them to get clear images of the uterus and developing fetus. When it comes to checking the heartbeat, the B-mode (brightness mode) is used to create real-time grayscale images. On top of that, some advanced machines also include M-mode (motion mode), which is excellent for measuring cardiac rhythms.
While B-mode shows you where the heart is, M-mode gives you that satisfying visual of the heartbeat pattern — the telltale rhythm pulsing across the screen like a mini EKG. For some farms, this confirmation is all they need to continue standard prenatal care. For high-risk pregnancies or valuable mares, regular heartbeat monitoring is often scheduled throughout the pregnancy.
When Is It Best to Check the Foal’s Heartbeat?
Timing matters. The earliest a heartbeat can be detected is typically around day 25 of gestation. After that, most equine veterinarians recommend follow-up scans at:
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Day 30-35: Confirm embryo viability
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Day 45-60: Monitor development and rule out twin pregnancies
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Day 90 and beyond: Observe fetal growth, movement, and continuing heartbeat rhythm
In the middle to late stages of pregnancy, transabdominal ultrasound may be used in addition to rectal exams. This involves placing the probe on the mare’s belly, especially when the fetus is no longer in reach rectally. At this point, the heartbeat becomes more consistent, and you may even be able to hear it using Doppler ultrasound, which translates the rhythm into audible sound.
Real Benefits on the Farm
So why has ultrasound become the go-to tool for fetal heart monitoring? Beyond the obvious answer of “because it works,” farms love it for a few practical reasons:
✅ Early Detection of Pregnancy Failure
Nothing is more frustrating — or financially devastating — than discovering a mare lost her foal weeks or months ago. Regular heartbeat checks help catch these losses early, allowing for quicker rebreeding decisions.
✅ Monitoring High-Value Mares
In racing and sport horse industries, some mares are considered priceless. If a mare has a history of reproductive issues or is carrying a valuable embryo, routine heartbeat scans give breeders constant reassurance.
✅ Stress-Free and Safe
Ultrasound is non-invasive, quick, and doesn’t require sedation. Most mares tolerate the process easily, making it perfect for routine monitoring without disrupting daily life on the farm.
✅ Easy Integration with Veterinary Records
Heartbeat data, alongside fetal size, position, and fluid measurements, can be saved and tracked over time. That means better medical records and smarter decision-making.
What a Normal Foal Heartbeat Looks Like
For anyone curious — yes, there’s a range of what counts as “normal.” In early gestation, the fetal heart rate is usually about 120 to 180 beats per minute. As gestation progresses, it gradually slows down, settling closer to 80-120 bpm in the later months.
A fluctuating or very low heart rate can signal distress, placental insufficiency, or infection. Farms with ultrasound experience (or working closely with a vet) can catch these warning signs and take steps early — whether that means adjusting nutrition, rest protocols, or preparing for potential foaling complications.
Twin Pregnancies and Heartbeat Confusion
Here’s a tricky one: twin pregnancies in mares can be dangerous, and detecting two distinct heartbeats is a major red flag. That’s why equine practitioners often recommend reducing twin embryos early (before day 16) if two are found.
If a second heartbeat is detected later — especially if it appears weak or mismatched — it could indicate a failing twin or misdiagnosis. That’s why scanning experience matters. Trained vets can identify overlapping heartbeats, fetal positions, and distinguish between a healthy foal and a problematic gestation.
Horse Owners Share Their Experiences
Many horse owners in the U.S., Canada, and Europe now share stories online about watching their unborn foal’s heartbeat flicker on a screen. Whether it’s a backyard breeder with one beloved mare or a full-scale operation, the emotional connection formed during these scans is unforgettable.
One breeder in Ireland shared:
“When the vet turned the screen and showed me the heartbeat, I teared up. It was the moment I really believed this foal was coming.”
In Australia, a farm manager noted:
“We scan our mares every couple of weeks through the early months. Seeing the heart flickering confirms all our hard work is paying off.”
These personal moments highlight why ultrasound isn’t just a tool — it’s a way to bond with the process and safeguard future generations of horses.
Practical Challenges: Not Always Smooth Sailing
Of course, ultrasound use in horses isn’t foolproof. Some mares can be fidgety or anxious during rectal exams, especially if they’re young or first-time pregnancies. It also takes a skilled hand to interpret the images correctly, especially when looking for something as tiny and fast as a heartbeat.
Equipment quality matters too. Older machines may not offer the resolution needed for early heartbeat detection. That’s why many top breeders invest in high-quality portable scanners, some even waterproof and barn-proof for daily use.
Weather, mare temperament, and vet availability can all make consistent scanning tricky. Still, for most farms, the benefits far outweigh the hassles.
Final Thoughts: A Window Into the Womb
Equine fetal heartbeat monitoring has come a long way from just “waiting and hoping.” Today, thanks to veterinary ultrasound, farms have a powerful, safe, and precise way to check in on unborn foals and ensure mares are progressing well.
The heartbeat is more than just a sign of life — it’s a reassurance, a guide, and sometimes, a lifesaver. Whether used once or regularly, this simple flicker on a screen helps farmers, vets, and horse lovers alike take better care of their animals, plan smarter, and sleep easier at night.