Musculoskeletal injury rates in Thoroughbred racehorses following local corticosteroid injection.
Authors: Whitton R C, Jackson M A, Campbell A J D, Anderson G A, Parkin T D H, Morton J M, Boden L A
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Local Corticosteroid Injection and Subsequent Musculoskeletal Injury in Thoroughbreds This retrospective analysis of 1,911 racehorses examined whether local corticosteroid injections (LCI)—administered intra-articularly, peritendinously, or intramuscularly—altered the risk of subsequent musculoskeletal injury requiring a minimum 6-month racing absence or retirement. Of the cohort, 392 horses received at least one LCI (predominantly bilateral treatments to the carpus and fore fetlock), whilst researchers tracked 219 musculoskeletal injuries overall using Cox proportional hazards modelling to compare injury rates before treatment, following injection, and in untreated controls. The pivotal finding was a nearly five-fold increase in injury hazard within 49 days post-injection (HR 4.83, 95% CI 3.54–6.61), with hazard ratios returning to baseline thereafter; notably, horses receiving repeat injections showed a two-fold greater injury risk than those treated once (HR 2.10), suggesting either progressive underlying pathology or cumulative therapeutic failure. The authors concluded that whilst the elevated short-term injury risk likely reflects progression of the pre-existing condition prompting treatment rather than injection-induced harm, any analgesic or anti-inflammatory benefit failed to offset the mechanical vulnerability of treated structures during the critical 7-week window. For practitioners, this reinforces the importance of conservative management post-injection, realistic client expectations regarding return-to-work timelines, and judicious decision-making when contemplating repeated treatments, particularly where single injections have failed to restore soundness.
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Practical Takeaways
- •Expect temporarily elevated musculoskeletal injury risk for 49 days following local corticosteroid injection; this increased risk likely reflects disease progression rather than treatment effect
- •Counsel horse owners that corticosteroid injections target symptom relief, not tissue repair, and do not reduce subsequent injury rates in racing Thoroughbreds
- •Monitor closely for 7 weeks post-injection; consider restricting work during this high-risk period, particularly in horses with pre-existing carpal or fetlock pathology
Key Findings
- •Local corticosteroid injection was associated with a 4.83-fold increased hazard of musculoskeletal injury compared to untreated horses (95% CI 3.54-6.61, P<0.001)
- •The elevated injury risk persisted for approximately 49 days post-injection, after which hazard returned to baseline levels
- •Carpal (49%), fore fetlock (22%), and forelimb tendon injuries (16%) were the most common MSIs in the cohort
- •Horses receiving multiple LCI had greater injury hazard (HR 2.10) compared to those receiving a single injection, suggesting underlying disease progression