Bigger Heart in a Performance Horse: What Does It Mean?

Results of a study published in American Journal of Veterinary Research showed that top-level Arabian endurance horses had larger hearts than their counterparts that did not perform as well. The research involved 34 Arabian horses used for endurance competition. Echocardiography was performed on all the horses to determine cardiac measurements. In 23 of the horses that were identified as elite performers, the left ventricle—the chamber of the heart that sends blood to the muscles—was larger and therefore able to circulate more oxygen during exercise.

The heart is constructed of muscle tissue, and like other muscles, it becomes stronger with exercise. Researchers who conducted this study granted that the cause-and-effect aspect of this research is unclear. It’s possible that the elite performers were born with larger hearts that gave them a performance edge, allowing them to become elite athletes. It’s also possible that the horses’ hearts were initially of an average size but became larger as the equines responded to intense training regimens. Finally, performance is the sum of many factors such as nutrition, health status, gender, rider’s skill, size and age of the horse, and the individual horse’s personality in addition to genetic makeup and training methods. Having a larger than average heart might be an advantage, but by itself, this one trait would probably not guarantee that a certain horse would be a winner in its performance discipline.