It takes a substantial “engine” to power a racehorse around a track at top speed, and a crucial component of that engine is a healthy respiratory system. Airway issues are, however, common in racehorses. The good news is there are ways to improve these athletes’ respiratory function and, thus, their performance.

At the seventh Welfare and Safety of the Racehorse Summit, held June 28 at the Keeneland Race Course, in Lexington, Kentucky, Susan Holcombe, VMD, MS, PhD, Dipl. ACVS, ACVECC, and Bill Casner teamed up to review racehorse respiratory health. Holcombe is a professor of large animal clinical sciences at the Michigan State University College of Veterinary Medicine, in East Lansing. Casner is a Thoroughbred owner and breeder who, along with Kenny Trout, founded WinStar Farm, in Lexington, Kentucky, and now operates Casner Racing LP.

Horses are unique, Holcombe explained, in that their athletic performance is limited by their pulmonary (lung) function rather than their heart function, as most other species are. As such, keeping the respiratory system healthy and functioning properly is key to facilitating good performance and overall health.

The airways are a conduit of tubes and small sacks that allow the horse to take in oxygen from the air and expel carbon dioxide. Oxygen is transported in the blood to skeletal muscle where mitochondria (tiny organelles within cells) use it to synthesize energy essential to muscle function.

At rest, a horse takes about 12 breaths and inhales about 5 liters of air per minute and has a ventilation rate of about 60 liters per minute. During intense exercise, like race training, however,