During exertion, equine cardiac output increases eight to 12 times over resting value, and the horse’s heart rate increases up to eightfold from the typical 32 to 36 beats per minute to a maximum of 240-plus beats per minute. | Photo: Erica Larson/The Horse

The horse’s heart is well-described in training texts and literature: It is big, giving, trusting, and can push the animal toward great feats of speed and strength. But as much credit as we give horses for their metaphorical hearts, the actual blood-pumping organs generally get far less attention than other bodily systems, said internist Virginia B. Reef, DVM, Dipl. ACVIM, ACVSMR, who specializes in equine cardiology.

As a remedy, the American Association of Equine Practitioners (AAEP) gave the horse’s heart a little love and invited Reef to present the Frank J. Milne State-of-the Art Lecture at its 2018 convention, held Dec. 1-5 in San Francisco, California. Reef, who serves as a professor and section chief in imaging at the University of Pennsylvania School of Veterinary Medicine’s (Penn Vet) New Bolton Center, in Kennett Square, has spent her 40-year career studying the equine cardiovascular system and treating heart disease.

“It’s an area that veterinary schools in the past overlooked—(people believe) horses don’t get cardiac disease or that it’s unimportant,” Reef said. “But there’s more and more recognition that cardiac disease actually is important, and there’s concern from the public and veterinarians about horse safety and sudden cardiac death