When a racehorse breaks down on the track, you’re not only faced with the devastating loss of a horse, but also economic loss and, potentially, an injured jockey. One of the most common sites of catastrophic injuries in Thoroughbred racehorses is the fetlock and its surrounding structures.

To try to prevent more of these injuries from happening, four veterinarians involved with the California Horse Racing Board and University of California (UC), Davis, Racing Injury Prevention Program recently studied past breakdowns and their causes. Erin McKerney, DVM, a veterinarian at the UC Davis J.D. Wheat Veterinary Orthopedic Research Laboratory, presented the team’s findings at the 2013 American Association of Equine Practitioners’ convention, held Dec. 7-11 in Nashville, Tenn.

"Fetlock injuries comprise over half of fatal musculoskeletal injuries among California racehorses," McKerney said. "Repetitive loading and fetlock hyperextension associated with training and racing subject fetlock-supporting musculoskeletal structures to degenerative and adaptive changes. These changes can weaken key structures, thus predisposing the fetlock region to catastrophic fracture."

This is fairly common knowledge among sport- and racehorse practitioners. The problem is pinpointing which pre-existing lesions put these horses as most risk for breakdown and how to detect them before the worst happens.

In their retrospective study, McKerney and her team analyzed post-mortem examination records of 358 California racehorses (Thoroughbreds, Quarter Horses, and one Arabian) that sustained catastrophic injuries between July 2011 and Ju