Factors Associated with Mortality in Ontario Standardbred Racing: 2003–2015

Abstract

Factors associated with mortality in standardbred racehorses were assessed through a retrospective annualized cohort study of all-cause mortality from 2003–2015 (n = 978) (identified in the Ontario Racehorse Death Registry). Race and qualifying data for official work-events were also gathered (1,778,330 work-events, 125,200 horse years). Multivariable logistic regression analysis revealed sex, age, and indices of workload and intensity and their interactions to be strongly associated with mortality. Track class, race versus qualifying performance, and work-event outcome (finish position, scratched, or failed to finish) also influenced mortality odds, which increased as performance slowed. Intense competition at higher performance levels and qualifying races at lower levels carried particularly high odds. Though occurring frequently, musculoskeletal injury was less frequent than all other presenting problems combined. Industry structure contributes to mortality through interaction between horse characteristics and the competition environment. This substrate may be amenable to management to minimize liability, but incident-specific triggers may represent chance factors and be relatively difficult to identify or control. Differentiating between substrate and trigger when studying specific clinical problems may provide greater clarity and yield in identifying underlying causes. Mortality may reflect a continuum of circumstances, cumulative impacts of which might be identified before a fatal event occurs.

Factors Associated with Fatality in Ontario Thoroughbred Racehorses: 2003–2015

“…In an analysis of standardbred fatalities, horses that did not finish (DNF) could easily be differentiated from those finishing late, since race records identify DNF in the race line and a finish position is not assigned. Identification of an association between finish position and liability to fatality in non-DNF horses in that study was thus independent of the influence of horses that failed to finish [66]. For the race events in the present analysis, reference must be made to full race charts to identify reasons for a horse coming last, while in some races there may be more than one DNF horse and each would have been given a sequential numeric finish position.…”

Race-Level Reporting of Incidents during Two Seasons (2015/16 to 2016/17) of Harness Racing in New Zealand

“…Within the current data set, it was also difficult to clearly differentiate race grade and track surface to compare the race grade effect. Harness racing data from Canada indicates that racing at higher ranking tracks was associated with a higher incidence of sudden death and accidents for horses failing to finish a race than in races at lower-ranking race tracks [ 4 ]. A similar pattern of greater MSI with higher grade racing was reported in Australian Thoroughbred racing with a higher incidence of musculoskeletal injuries reported on metropolitan racetracks compared to country track [ 9 ].…”

“…Within New Zealand, the structure of the harness racing industry and Standardbred breeding industry have been described [ 2 , 3 ]. There are limited data on the training of standardbreds internationally, [ 4 ] or from within New Zealand [ 5 ], and little information on injuries and injuries associated with racing events [ 6 ]. This trend is also observed in the international literature with limited data on racing related injuries in standardbred harness racing [ 4 , 7 ].…”

“…International and domestic data have suggested that potential risk factors for race day injury in Thoroughbred racing include track surface, track condition, race distance, race class, age of horse, training intensity, and number of starters [ 9 , 10 , 11 ]. Within harness racing, Physick-Sheard, Avison, and Sears [ 4 ] identified that sex, age, track class, performance history, and workload affect the likelihood of horse mortality on race day. However, they did not examine non-fatal injuries.…”