Fatal musculoskeletal injuries of Quarter Horse racehorses: 314 cases (1990-2007).

The study explores causes of death in Quarter Horse racehorses in California specifically focusing on musculoskeletal injuries. It shows that majority of fatalities among these horses are due to musculoskeletal issues, mostly occurring during races and in the forelimbs, with stress remodeling of bone indicating that some fractures might be preexisting.

Research Methodology

• The study is a retrospective case series, analysing 314 Quarter Horse racehorses that had suffered musculoskeletal injuries and undergone necropsies through the California Horse Racing Board Postmortem Program from 1990 to 2007.
• Postmortem pathology reports of these horses were retrospectively reviewed. The assessment focused on detailing the musculoskeletal injuries by anatomic region.
• Data of Quarter Horse starts and starters for the same period was obtained from a commercial database to determine the fatal injury incidence rate.

Research Findings

• Out of 443 Quarter Horse racehorses that died during the 18-year study period, musculoskeletal injuries accounted for 314, representing 71% of the total deaths.
• The death rate attributed to musculoskeletal injuries was calculated to be 2.0 deaths/1,000 race starts and 18.6 deaths/1,000 horses that started a race.
• The study revealed that 84% of the injuries occurred during racing and 81% in the forelimbs.
• The most common fatal musculoskeletal injuries were found to be metacarpophalangeal and metatarsophalangeal joint (fetlock) support injuries (40%), followed by carpal (24%), vertebral (10%), and scapular (8%) fractures.
• Fractures of some bones were found to be consistent with those in Thoroughbred racehorses, and evidence of preexisting stress remodeling of the bone was discovered for some fractures.

Conclusion and Implications

• The study concluded that knowledge of the common locations and types of fatal musculoskeletal injuries in racing Quarter Horses is crucial to improve veterinary practitioners’ ability to detect mild injuries early.
• Early detection can enable horses to rest and prevent the occurrence of catastrophic injuries. It also highlights the need for more in-depth attention to pre-race assessments to identify signs of preexisting conditions that could lead to fatal incidents.