The effect of stress fracture occurring within the first 12 months of training on subsequent race performance in Thoroughbreds in Hong Kong.
Authors: Johnston Anna S, Sidhu Anhadbir B S, Riggs Christopher M, Verheyen Kristien L P, Rosanowski Sarah M
Journal: Equine veterinary journal
Summary
# Editorial Summary Young Thoroughbreds entering racing in Hong Kong face a 1.7% risk of stress fracture within their first year, with the humerus and tibia accounting for 70% of cases—a finding that underscores the vulnerability of the immature skeletal system during the critical transition from training to racing. This retrospective matched case-control study analysed nuclear scintigraphy records from 5,180 imported horses between 2006 and 2018, comparing 87 horses with documented stress fractures to controls matched on import date, and tracking their subsequent racing performance and career longevity. Fractured horses lost a median of 63 days of training and subsequently completed four fewer race starts within 12 months of diagnosis, translating to approximately HK$206,000 in lost earnings—a substantial economic impact during the critical early career phase. Despite these significant short-term setbacks, overall career length proved comparable between injured and control horses (median ~2 years 3 months), suggesting that appropriately managed stress fractures do not necessarily preclude long-term racing careers. For veterinary teams and trainers managing young racehorses, these findings highlight the importance of early detection and structured rehabilitation protocols that allow return to competitive performance, whilst acknowledging that the economic cost of injury during this foundational period remains considerable regardless of eventual career duration.
Read the full abstract on PubMed
Practical Takeaways
- •Young racehorses in their first year of training face a 1.7% risk of stress fracture; early detection via scintigraphy allows intervention before severe performance loss occurs
- •Expect fractured horses to miss approximately 2 months of training and have reduced race starts and earnings in the year following diagnosis, but full career length is not necessarily compromised
- •Humerus and tibia account for 70% of stress fractures in newly imported racehorses—focus conditioning and monitoring on these high-risk sites during the critical first 12 months
Key Findings
- •Stress fracture incidence was 1.7% (95% CI 1.4%-2.1%) within the first 12 months of training in Hong Kong racehorses
- •Humerus (42.0%) and tibia (28.0%) were the most common stress fracture sites
- •Horses with stress fractures had a median of 4 fewer race starts (P<0.0001) and lost HK$206,188 in earnings (P=0.007) within 12 months post-diagnosis compared to matched controls
- •Career length did not significantly differ between fractured and control horses (median 2 years 3 months; P=0.2)