HISA advisory flags risk factors behind fatal hindlimb fractures

The Horseracing Integrity and Safety Authority on Thursday announced the release of a new Equine Health Advisory identifying key risk factors associated with fatal proximal hindlimb fractures in Thoroughbreds. The advisory, based on data drawn from the HISA Portal, provides practical guidance for trainers and veterinarians on how to help prevent these catastrophic injuries.

In 2024 and 2025, regulatory veterinarians at covered racetracks reported 28 fatal tibial (12) and pelvic bone (16) fractures. Most (75%) fractures occurred during training; 25% occurred during racing.

Approximately 40% of horses with fatal proximal hindlimb fractures reported to HISA had 10 or fewer high-speed furlongs recorded within the 60 days prior to the fracture occurring.

Fatal tibial fractures

Approximately 40% of horses with fatal tibial fractures had zero recorded lifetime high-speed furlongs; 50% had 10 or fewer high-speed furlongs recorded in the 60 days prior to fracture.

Four of these horses (roughly 15%) had been on the Veterinarians' List as unsound at least once in the previous year, underscoring the need for careful attending veterinary evaluation once these horses are flagged by regulatory veterinarians. Two others were older, unraced horses: one was unraced at 4 years old; one was unraced at 5 years old. Both sustained fatal tibial fractures.

Fatal pelvic bone fractures

Approximately 80% of fatal fractures of the pelvic bones occurred in fillies and mares. Fatal tibial fractures, by contrast, occurred more evenly across both sexes.

This data suggests that a lack of high-speed exercise, such as in horses beginning training or returning from an extended layoff, may pose a significant risk for fatal proximal hindlimb fractures – as it does for proximal forelimb fractures.

This is the third Equine Health Advisory that HISA has issued, following advisories on proximal forelimb fractures and exercise-associated sudden death. Sharing these insights from the HISA Portal supports better-informed care, promotion of best practices and reduction of the risk of equine injuries and fatalities.

“It’s important that HISA utilizes the data we collect to draw insights and share learnings with the industry,” said Dr. Jennifer Durenberger, HISA Director of Policy and Industry Initiatives. “This advisory, like the proximal forelimb fracture advisory, aligns with HISA’s commitment to data-driven safety and education among industry stakeholders.”

The full advisory has been distributed to all trainers and veterinarians registered in the HISA Portal and is also available on www.hisaus.org under the Resources section.