Heart Monitoring Devices for Horses

Learn about devices designed to measure equine athletes’ cardiac function and maximize performance

Engineers and researchers have been designing “ECG” readers that are more practical for field use. | Courtesy Eleonore Groux Photography

The past decade has seen monitoring devices for humans soar in popularity. As wearable and portable equipment that tracks activity, heart rate, respiration, and more trickles into the veterinary world, horse owners are starting to see a wide range of commercial options for monitoring their horses’ cardiac function, as well.

But do these devices work? And if so, for what?

To help you sort through the options and decide which—if any—device is right for your horse, we’ve gone to the equine heart monitoring experts. In this article you’ll see not only how these devices work but also what information they might give you.

Pulse Readers

The most basic monitors in human medicine simply detect arterial pulsation (blood flow through the vessels), says Gunther van Loon, DVM, PhD, Dipl. ECEIM, Assoc. Member ECVDI, head of the Equine Cardioteam and professor in Ghent University’s Faculty of Veterinary Medicine, in Belgium. Some equine devices have been developed with a constricting cuff around the horse’s limb, similar to those used for measuring human blood pressure, but scientific data has yet to validate this technique, he says. Others shoot LED beams through the skin to measure how light scatters in the blood during a heartbeat. Photoplethysmography, as it’s called, works well on human wrists, but it’s not as reliable in horses due to their skin pigmentation, which interferes with the light beams.

Photoplethysmography also doesn’t work during movement, so these devices measure heart rate periodically and provide an average. “It might be a mean value over five or 10 beats or over a minute or two,” van Loon says. “So it’s really just a rough estimate.”

ECG and Heart Rate Monitors

Devices that measure the heart’s electrical activity can give more accurate readings, van Loon says. Electrical signals cause the heart—a complex muscle made up of two atrial chambers and two larger ventricular chambers—to contract before it relaxes again. Electrodes placed over the heart can pick up those signals and provide detailed data about the heart’s electrical activation in a recording known as an electrocardiogram (ECG).

“So you might have a series of beats which are all pretty much the same, and then suddenly one is very different, and you’ve detected an irregularity,” van Loon explains.

Veterinary-quality ECG machines require the electrodes be placed in specific locations on the chest to ensure accurate electrical readings. They also require a skilled veterinarian’s interpretation. Keeping the electrodes and device in place for prolonged recordings or during exercise often requires a bandage or girth that can make measurement impractical and time-consuming in the field, van Loon says. Worn too long, they might cause skin irritation or even sores. So engineers have been designing gel-free, clip-free “ECG” readers that simply strap around the horse’s heart girth.

“People have been trying to do this for many years,” says Katharyn Mitchell, BVSc, DVM, PhD, Dipl. ACVIM-LAIM, assistant professor of large animal medicine at Cornell University, in Ithaca, New York. “There was special electrode fabric, and there were plastic electrodes. Then there was just the girth with the electrodes in it, and then all sorts of different iterations.”

Most of these designs couldn’t detect the heart’s electrical signals consistently or picked up additional information—known as artifacts—that interfered with the reading, she says.

Antonio Lanata, PhD, an engineer at the University of Pisa, in Italy, says his team has been able to scientifically validate such a device. Their jerseylike, machine-washable ECG monitor stretches comfortably around the horse’s heart girth and detects electric cardiac signals using tiny electrodes woven into the garment’s threads. Because the horse sweats beneath the material, it doesn’t require gel for good, consistent signal transmission. While their equipment is already being used in emotional response and human-animal bonding research (more on this in a bit), it’s not yet ready for a commercial market.

Among the many wearable ECG monitors already available to horse owners, one shows strong potential and seems to work to a certain degree, says Mitchell. Designed in France, the monitor’s electrode-embedded girth and sensor fitted into a saddle pad appear to provide fairly accurate ECG readings along with global positioning satellite (GPS) data. “It has one of the better (ECG) signals I’ve seen,” she says. “But it’s still not perfect.”

For brief ECG monitoring in the barn, owners can use a commercial handheld device they hold against the horse’s side, Mitchell says. This is an inexpensive home solution for recording horses’ ECG at rest. “This is what I recommend people use if I know a horse has something like an arrhythmia, and we want to catch it at home, or if the horse is collapsing, and we want to check the heart rate when it collapses, for example,” she says. “But it’s no good during exercise.”

A compromise is a device that doesn’t run a full ECG but, rather, detects the biggest electrical spikes in each beat, which still allows for beat-to-beat monitoring, says Mitchell. This popular commercial model was developed in Finland by human heart rate monitoring pioneers and is being used in equine fitness and emotion research as well as in training barns.

Currently, though, there’s no gold-standard device on the market, says Mitchell.

What You Can Learn About Training

As one of the greatest physical stressors horses can experience, exercise is only beneficial when the body can recover from each session, says Giuseppe Piccione, PhD, DVM, a professor in the University of Messina’s Faculty of Veterinary Medicine, in Italy. This recovery requires a full-body effort involving key regulatory systems, including the cardiovascular system. “Failure to restore balance can have a negative impact on animal health status and the physical performance of the athlete,” says Piccione, whose team has been studying the physiology of exercise in sport horses through heart rate monitoring and other parameters since 1992.

Heart rate monitoring provides valuable feedback about those recovery efforts, says Piccione’s colleague and research teammate Francesca Arfuso, BSci, PhD. “A heart rate monitor is the best way of monitoring the health, recovery time, effort, and efficiency of horses when training and recovering from races (and other athletic exercise),” she says. “Detailed heart rate data enable trainers to track the fitness and wellness of their horses and structure their training plans accordingly. These aspects are of paramount importance, especially in the assessment of fitness and health status of sport horses.”

When collecting exercise-related data for professional interpretation, “you’re trying to track changes over time and modify training accordingly,” Mitchell says. “You want to recognize when you’re approaching peak fitness and also recognize when you’re training too much and you need to pull back, and when you might be approaching an injury.”

Heart rates vary considerably according to training level and exercise type, says van Loon. “What’s most important is finding trends for your horse, and then you can relate to numbers,” he says. “Then you can say, ‘Okay, this is normal for my horse.’ And if that suddenly changes, well, something might be wrong.”

Heart rate variability—a measure of the variation in time between each heartbeat (monitored with ECG or heart rate monitors)—can alert the user to changes in the autonomic nervous system that could indicate poor recovery from a previous exercise session, or overtraining in general, says Piccione.

Devices are unlikely to predict sudden death, adds van Loon. “Monitoring might, however, flag some horses that have a higher risk and need to be checked,” he says. “But we need to accept that we will not be able to predict all cardiac risks or possible deaths.”

Both heart rate and ECG monitors “represent a valid contribution to research in the field of sports physiology and medicine,” says Arfuso. “The use of these new devices for heart rate assessment in athletes opens up new scenarios and opportunities for sport horse cardiovascular health monitoring.”

The Critical Importance of Scientific Validation

Dozens of commercial product manufacturers claim to provide horse owners with valuable heart monitoring feedback, often with beautiful designs and fancy apps. But that doesn’t make them reliable, our sources say. The only way to ensure a product works is if it has sound, unbiased scientific research backing it.

“The scientific background is fundamental, because the information a product is providing is important for health and welfare,” says Antonio Lanata, PhD, of the University of Pisa, in Italy. “It has to be tested in laboratory conditions and compared with literature in the research community to be sure that what they’re saying the product is telling you is correct.”

“This is often the problem,” says Gunther van Loon, DVM, PhD, Dipl. ECEIM, Assoc. Member ECVDI, of the University of Ghent, in Belgium. “It’s very easy to put a sensor on a horse, and you get a signal. But you can get all kinds of signals from a horse. So what do those signals mean? There should always be science behind it.”

Signals can come from the girth, the rider, hair, muscles, and more, making it difficult to get true electrocardiogram (ECG) or heart rate data, says Katharyn Mitchell, BVSc, DVM, PhD, Dipl. ACVIM-LAIM, of Cornell University, in Ithaca, New York. Worse, manufacturers often claim their products have been scientifically validated when that “science” was carried out by the company itself, lacking in peer review and true scientific method, which “doesn’t really count,” she says. “I think a lot of the products come to market very quickly, without sound validation. You want scientific validation that’s been published in academic journals.”

—Christa Lesté-Lasserre, MA

What You Can Learn About Health

Heart monitors can also give insight into underlying diseases or provide much-needed feedback about a horse’s response to treatment, Piccione says. “Since the system is wireless and remotely accessible, vets can safety monitor horses in isolation from a distance, keep tabs on a colic case, or provide long-term monitoring for horses with suspected arrhythmias,” he says.

Products available to consumers allow owners to do much of that monitoring at home, says Mitchell. “Sometimes we’ll do an ECG and see something that looks a little more dangerous, and so we’ll tell people, ‘Okay, you could try a heart rate monitor at home,’ ” she says. “They can get a feel for what the trends are and know when to stop exercising the horse when the rate gets over a certain amount and let us know what they find.”

Those devices must be ECG monitors to identify the type and, thus, importance of arrhythmias, says van Loon. “Non-ECG heart rate monitors generally do not detect the type of arrhythmia or do not detect irregular heartbeats at all,” he says.

Heart rate monitors can still be useful for health monitoring, as they can reveal trends over time. “For example, you monitor your horse in the pasture or whenever you ride, and suddenly you see increases in his normal heart rate,” he says. “This could be heart disease or lung disease, or maybe the horse has pain, such as lameness or colic. They can be helpful for diagnosing things that might not always have such visible clinical signs.”

For Mitchell, heart rate and ECG monitors might also help scientists discover signs an equine athlete’s heart is starting to wear out—but that’s a bit far off. “We still don’t have a lot of concrete data that lets us say to people that it’s starting to get unsafe, and it’s time to retire the horse,” she says.

What You Can Learn About Emotions

The heart doesn’t just react to exercise and illness; it’s also an important indicator of emotional reactions, Piccione says. That’s why so many equine research projects include heart rate monitoring. It reflects how horses might be feeling physically and mentally.

At rest, horses have low heart rates of around 40 beats per minute, reflecting a strong parasympathetic (pertaining to the part of the nervous system responsible for the “rest and restore” response) tone, Mitchell says. Horses also have a strong sympathetic nervous system, which kicks in when they think they need to run from predators, for example. That stress leads to significant increases in heart rate.

In a practical sense, owners can use heart monitoring to identify the situations that stress their horses and to what extent, says Lanata, who’s spent the past 10 years studying the link between horses’ heart rates and emotions. It has to do with how the autonomic and peripheral (outside the brain and spinal cord) nervous systems communicate with each other, leading to physical changes in the heart in connection with emotion, he says.

Scientists can “read” emotional states in ECG recordings, not by looking for specific numbers but through changes in signals over time, says Lanata. “It’s not like a thermometer,” he says. “To get information about the horse’s mental health, you always need a situation of comparison.”

One application could be investigating how stress affects competition horses, Arfuso says. “Changes in heart rate between training sessions and official competitions, where the emotional component also affects heart rate, are worthy of investigation,” she says.

This could involve monitoring stress levels at home to understand what might be causing stress and find ways to reduce it, says van Loon.

Lanata is particularly interested in what ECG monitors might tell us about the interspecies bond horses and humans develop. In collaboration with colleague Paolo Baragli, PhD, Lanata and his team have been recording data about heart rate variability in both horses and people. When heart rate variability starts to align, as they’ve seen in their preliminary work, it suggests an emotional bond, he says.

Practically speaking, such knowledge could tell us how horses feel about specific humans, which might affect their welfare and performance—something his team would like to study.

Getting Vet-Level Monitoring

Even with the best technology and validated science, owners must remember these devices are just devices, not veterinarians, our sources say. They can point to useful trends and interesting information, but they can’t replace veterinary knowledge and tools.

“When you see abnormalities, have the horse checked, but don’t panic, and don’t blindly rely on your device,” van Loon says. “It’s just an additional tool, and people should accept that certain errors will exist.”

Vets can use more advanced and precise equipment in their clinics and take other health factors and history into consideration for an appropriate diagnosis and, if needed, treatment plan, Piccione says.

Take-Home Message

When properly validated through independent studies, home heart rate monitors could provide helpful information about our horses’ health, emotions, and adaptations to training. “The hardest part about all this is doing your homework and knowing which devices to use,” Mitchell says. “There’s a lot out there, and you can really get caught in the weeds.”