When it comes to the equine heart, size matters, says Lesley Young, BVSc, PhD, DVA, Dipl. ECEIM, DVC, MRCVS, who completed research on the topic while at the Animal Health Trust in Newmarket, Suffolk, United Kingdom. In her June 3 presentation at the 24th annual American College of Veterinary Internal Medicine Forum held in Louisville, Ky., Young explained the significance of equine heart size, its ability to oxygenate the body, and its use as an athletic predictor in untrained racehorses.
Trainers, owners, and researchers have long pondered the effects of a large heart (one that is naturally occurring and not a result of disease), and have even attempted to use heart size as a predictor of athletic ability.
"The Thoroughbred industry is worth millions and millions of dollars," Young said, explaining why horse owners might be interested in equine heart size. "If it's a possibility of being able to predict which of these horses are going to be better racehorses, it's something people are going to want to buy into."
To determine if heart size actually plays a role in athletic performance, Young examined data from 483 race-fit Thoroughbreds. Using VO2max (the best indicator of cardiorespiratory performance) and echocardiography, she categorized horses by anaerobic capacity and heart size. VO2max incorporates both the consumption and the delivery of oxygen to the muscles.
Young said her results indicated, "the first direct evidence that cardiac size influenced athletic performance in a group of Thoroughbreds."
However, she said, "The data doesn't show that echocardiography can predict performance in untrained animals. It does give us evidence that we might be able to."
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.