horse heart function

If you have to restrain a horse every time you want to evaluate his cardiac function, you’re probably not getting a realistic view of how his heart works when he’s in motion. Yet, a heart’s electrical function is the only continuously measurable variable in moving horses, which can leave out critical information related to the heart’s mechanical functions. So Swiss researchers recently validated a system that detects and records electrical and mechanical cardiac data simultaneously, while horses are free to move about as they please.

“This new monitor is a completely noninvasive, wireless, wearable device that allows continuous monitoring of the heart’s electrical and mechanical functions, heart sounds and murmurs, body position, physical activity, and respiratory effort,” said Colin Schwarzwald, DVM, PhD, an equine internist and cardiology specialist in the University of Zurich Vetsuisse Faculty Equine Department, in Switzerland.

“During recordings, horses can freely move and do not have to be restrained in any way,” he said. “This allows long-term monitoring in a natural environment, to study normal cardiac physiology but also to monitor cardiac function in horses with heart disease.”

Originally developed for human medicine, the monitor registers electrical and sound data continuously for up to several days. The researchers wanted to see whether they could adapt this device for use on equine patients, so they found a safe way to attach it to a modified surcingle. Then, they collected data on 123 healthy, unclipped horses 10 hours a day for several days in summer and fall as the animals moved freely.

The scientists ran into a few technical difficulties, such as the device moving out of place, switching off by itself, or falling off the surcingle. However, for the most part, the tests were successful. The monitor allowed scientists to pick up and record nonstop electric and mechanical heart data from these horses during their daily routines.

What’s more, the data collection was easy, the team said. The recorded information passed from the device over Wi-Fi to a computer to be processed, where it provided a history that could be analyzed later by a skilled professional.

“Recordings can be easily obtained without prior expertise, and subsequent analyses can be done remotely by trained experts,” Schwarzwald said.

The technology complements the remote noninvasive electroencephalogram that allows researchers to record brain activity in free-moving horses. Both devices make it possible to carry out important clinical tests on horses without having to restrain them. Restraint can affect readings and compromise long-term welfare, he said.

The two tools might work in a complementary way, Schwarzwald added. “Brain injury can influence heart function; stress would influence both activity of brain and heart (and could potentially be detected and quantified with appropriate monitoring of brain and heart function); and clinical monitoring during sedation or general anesthesia might be facilitated and improved with combined use of these technologies,” he said.

The team conducted the current study to make sure the device worked on horses, but further research will focus on the monitor’s ability to help diagnose and monitor horses with cardiac disease, Schwarzwald said. In the meantime, it’s showing promise in helping clinicians pick up critical data about their equine patients’ heart function.

“While there is still room for improvement and development with respect to device attachment and consistent recording quality, acoustic cardiography has potential to provide added value over conventional diagnostic tools such as echocardiography, systemic blood pressure measurements, or cardiac catheterization,” the researchers stated.

The device should become available to clinicians after further field testing is completed, Schwarzwald said.

The study, “Assessment of systolic and diastolic function in clinically healthy horses using ambulatory acoustic cardiography,” was published in the Equine Veterinary Journal.