When 2010 Horse of the Year Zenyatta crossed the finish line for the last time, most race fans focused on the fact it was the first loss of her career. But what might be even more notable is that it was also her 20^th start–unusual in an industry that has seen an overall decline in starts (down to 6.11 per horse per year in 2010, according to The Jockey Club).

One of the reasons researchers propose for this decline is the modern-day Thoroughbred’s questionable durability. David Horohov, PhD, William Robert Mills Chair at the University of Kentucky’s Gluck Equine Research Center, however, believes the breed is not necessarily becoming more fragile, but rather more susceptible to injury due to breeding strategies, training methods, and increased drug use. During the Veterinary Science Seminar "The Effect of Training and Nutritional Supplementation on Exercise-Induced Pro-Inflammatory Cytokine Gene Expression in Two Year Old Thoroughbreds," held March 20 in Lexington, Ky., he explained how we might ultimately be able to identify individuals at risk for injury and, thus, try to prevent those racing and training injuries from occurring in the first place.

The statistics in racehorse "wastage" due to injury are shocking: Less than 60% of 2-year-olds in training race, and less than 80% of those continue to race as 3-year-olds, said Horohov. Career-ending injuries are, for the most part, musculoskeletal and include bowed tendons, suspensory ligament injuries, fractures, splints, and osselots (traumatic arthritis of the fetlock joint), among others.

Horohov presented the theory that these injuries are often the result of mild to moderate damage occurring over time at a rate that exceeds the affected tissues’ healing capabilities. He believes if researchers can develop a method to identify at-risk horses based on inflammatory response, they could prevent more injuries