Meta-analysis of risk factors for racehorse catastrophic musculoskeletal injury in flat racing

Warmblood fragile foal syndrome type 1 mutation (PLOD1 c.2032G>A) is not associated with catastrophic breakdown and has a low allele frequency in the Thoroughbred breed

“…Given the critical nature of these injuries, numerous epidemiological studies have focused on identifying key risk factors for racehorse fatality, with close to 300 different factors investigated. A recent meta‐analysis comparing 65 studies from 1990 to 2017 identified several horse‐specific (age, sex, and race class), race‐specific (track conditions, race distance, and field size) and management‐specific (time since previous start, number of starts, and previous injury, among others) factors that demonstrate consistent evidence for risk of catastrophic injury at repeatable sites due to cycle loading of the limbs in high speed work . Data from several studies support pre‐existing lesions at the distal end of metacarpal three or metatarsal three as a predisposing risk factor for catastrophic fetlock injuries .…”

“…Catastrophic fractures, resulting from significant bone or soft tissue injury, carry a poor clinical prognosis and are the most common cause of euthanasia or spontaneous death in racehorses . Investigating equine catastrophic musculoskeletal injury over a span of 27 years from 21 published studies showed a pooled incidence of 1.17 (0.90–1.44, 95% CI) injuries per 1000 starts . The Equine Injury Database, which tracks the frequency, types and outcome of racing injuries in the United States across 118 tracks since 2008, recently reported fatality rates for 2018 to be 1.68 per 1000 starts (http://jockeyclub.com/default.asp?section=Advocacy%26area=10).…”

Thoroughbred Racehorse Welfare through the Lens of ‘Social License to Operate—With an Emphasis on a U.S. Perspective

“…However, in the primary study of flat racing in North America, the condition of the track, evaluated for dirt and off-dirt surfaces, was not found to be significant [57]. In contrast, a more recent meta-analysis using studies from a number of different countries suggests that the type of surface may be less of a factor and that the surface's condition is significant [58]. Given the low quality of the data and inconsistent definitions used to define off-dirt versus dirt surfaces, the inconsistency in the significance of outcomes is not surprising.…”

“…A 5 year review of 1,891,483 race starts by 154,527 Thoroughbred racehorses (United States and Canada, 2009-2013) based upon data from the Equine Injury Database™ found 1.9 fatal injuries/1,000 race starts [57]. A more recent meta-analysis of peer-reviewed literature from 1990 to 2017, representing data from six countries, found catastrophic musculoskeletal injury at the rate of 1.2 per 1000 race starts [58]. While these numbers may be seen by some as 'the price of doing business' in a highly demanding, highly athletic equine sport, others recognize that the industry needs to strive harder to achieve as close to zero catastrophic breakdowns as possible.…”

“…The effect of surfaces on the incidence of catastrophic injury is supported by the literature, while the effect of surfaces on the overall length of a racing career is less well understood [57,58]. In the annual results from the Equine Injury Database™ maintained by The Jockey Club, synthetic surfaces reduce overall injury rates from 2.0/1000 starts on dirt to 1.2/1000 starts on synthetics [59].…”