Antonio M. Cruz, DVM, MSc, DrMedVet; Zvonimir Poljak, DVM, PhD; Catherine Filejski, DVM; Mark L. Lowerison, BS; Kyle Goldie; S. Wayne Martin, DVM, PhD; Mark B. Hurtig, DVM, MVSc

Am J Vet Res 2007;68:1370–1375 

Objective: To determine characteristics, incidence rate, and possible associations with selected demographic characteristics of catastrophic musculoskeletal injuries (CMIs) in Thoroughbred racehorses.

Animals: 76 Thoroughbreds with CMIs. Procedures: Incidence rates of CMIs during racing or training were calculated with number of CMIs as the numerator and overall numbers of races or training events during 2004 and 2005 as the denominators. Exact 95% confidence intervals were calculated. Associations between incidence and dichotomous exposure factors, nominal factors, and ordinal factors were determined. Only univariable associations were examined.

Results: 76 horses were euthanized because of CMI and represented 2.36 and 1.69 deaths/1,000 racing starts in 2004 and 2005, respectively. Of these, 57 were euthanized within 60 days before or after a race, which yielded a point incidence of 1.05/1,000 racing starts and 0.39/1,000 training starts.

Conclusions and Clinical Relevance: Incidence rate of CMIs at 2 Ontario racetracks was similar to that at other North American racetracks. A cumulative death rate of 1 to 2 deaths/wk should be considered typical when designing prevention strategies and offers a baseline value for measuring improvement.