Elite, Non-Elite Endurance Horse Hearts Compared

Elite, Non-Elite Endurance Horse Hearts Compared

When compared to their non-elite counterparts, elite endurance horses had fewer cardiovascular abnormalities and significantly different cardiac dimensions that could provide a greater cardiovascular ability and aerobic capacity.

Photo: Anne M. Eberhardt/The Horse

Editor's note: This article is part of TheHorse.com's ongoing coverage of topics presented at the 2012 American College of Veterinary Internal Medicine Forum, held May 30 - June 2 in New Orleans, La.

Many equestrians agree that it takes a horse with a special heart, mind, and athletic ability to reach the upper echelons of their sport. But now scientists have confirmed at least one part of this theory: Recent study results indicate upper level endurance horses have some different cardiac specifications than their lower level counterparts.

Mary M. Durando, DVM, PhD, Dipl. ACVIM, of Equine Sports Medicine Consultants, in Newark, Del., discussed the results of a study that compared elite and non-elite endurance horses' echocardiographic measurements at the 2012 American College of Veterinary Internal Medicine Forum, held May 30 - June 2 in New Orleans, La.

"In Thoroughbred racehorses an association has been made between caliber of racehorse, maximal oxygen consumption, and certain echocardiographic variables in longer, more aerobic races," Durando explained. "The purpose of this study was to determine if performance ability is related to echocardiographic indices of cardiac dimensions or function in endurance Arabians, because the sport has such a large demand on aerobic function."

Durando and colleagues evaluated 22 elite endurance horses and 18 non-elite horses, all Arabians between the ages of 7 and 17 years; horses were classified as elite or non-elite based upon recent finishes in specific American Endurance Ride Conference 100-mile rides.

Key findings, Durando relayed, included:

  • Cardiac abnormalities that could negatively affect performance and/or horse and rider safety--significant valvular regurgitation (backflow of blood from the lower to the upper heart chambers ) and/or ventricular dysrhythmias (abnormal rapid heart rhythms originating in the organ's lower chambers)--were identified in four non-elite horses;
  • No significant abnormalities were found in the elite group; and
  • Horses in the elite group had, on average, significantly larger left ventricular internal diameter, interventricular septal wall thickness, and calculated left ventricular mass and stroke volume than non-elite horses.

"(These factors) could correspond to greater cardiovascular ability and aerobic capacity and, thus, superior performance in this group of horses," Durando said.

She cautioned that "many other factors contribute to racing ability" and that the study results should be tested on an independent group of horses.

About the Author

Erica Larson, News Editor

Erica Larson, News Editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in three-day eventing with her OTTB, Dorado, and enjoys photography in her spare time.

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