Musculoskeletal injuries (MSI) sustained during races are a major concern for both equine welfare and jockey safety. While previous studies have primarily focused on the fractures diagnosed on race day, not all fractures are immediately identifiable. This study aimed to describe the epidemiology of race-related fractures in the Japan Racing Association (JRA) over five racing seasons, with emphasis on time to diagnosis.
Data on MSI events, including fracture and partial tears of tendons or ligaments suspected to have occurred during racing, were extracted from the JRA’s medical record database. Incidence rates per 1000 starts were calculated, and anatomical fracture sites were categorized. The number of days from the race to definitive diagnosis confirmed by imaging modalities (radiography, ultrasonography, or MRI) was determined.
A total of 164 catastrophic MSI cases were identified (0.71 per 1000 starts), of which 159 cases were diagnosed on race day. The most common anatomical site of catastrophic MSI was the forelimb fetlock (54%), followed by the hindlimb fetlock (15%). Among the 3242 non-catastrophic MSI cases (14.1 per 1000 starts), 103 involved partial tears of tendons or ligaments accompanied by overextended fetlocks, which were all diagnosed on the race day. Of the 3139 non-catastrophic fracture cases, 2779 cases (12.1 per 1000 starts) were diagnosed within 5 days (median; 2 days, range; 0–74 days), while 407 (1.77 per 1000 starts) were diagnosed on race day. The most common anatomical site of non-catastrophic fractures diagnosed within 5 days was carpal joint (60%), followed by forelimb fetlock (28%).
These results suggest that post-race follow-up over several days is essential for the accurate detection of fractures. Furthermore, the high incidence of carpal fractures underscores the need for further research into the underlying mechanisms of carpal joint injury to support prevention strategies and enhance equine welfare.