Prevalence of, and factors associated with, musculoskeletal racing injuries of Thoroughbreds
Authors: Peloso J. G. , Mundy G. D. , Cohen N. D. 
Published: December 2023

Abstract
All horses diagnosed by a commission veterinarian of the Kentucky Racing Commission as having sustained a musculoskeletal injury, defined as an obvious change in soundness immediately before, during, or after a race held between Jan 1, 1992 and May 31, 1993 were included in a study to determine the prevalence of and factors associated with racing injuries involving the musculoskeletal system of horses competing at 4 Thoroughbred racetracks in Kentucky. During the 17-month study, there were 35,484 racing starts among 7,649 horses in 3,824 official Kentucky Racing Commission races. During this period, 132 musculoskeletal racing injuries were diagnosed among 117 horses. Twenty-eight injured horses were male, 46 were geldings, and 43 were female. The prevalence of horses with racing injuries per racing start was 0.33% (117/35,484). The injuries of 51 horses were classified as catastrophic, and 66 as noncatastrophic. The prevalence of horses with catastrophic injuries per racing start was 0.14% (51/35,484).
The proportion of horses with injuries of the left forelimb, sesamoid, and third metacarpal bone in the catastrophic group was significantly (P < 0.05) greater than those of horses in the noncatastrophic group. The proportion of horses with injuries of the superficial digital flexor tendon among those in the catastrophic group was significantly less than that of horses in the noncatastrophic group.
The distance of the race was significantly shorter and the number of turns less among horses with catastrophic injuries than among horses with noncatastrophic injuries. The proportions of horses injured at the last turn in the race (stretch turn) and the straight stretch of track before the last turn (back- stretch) among the catastrophic group were significantly greater than those among horses in the noncatastrophic group. Injuries detected after the race among horses in the catastrophic group were significantly less common than those among horses in the noncatastrophic group. The proportion of horses removed from the racetrack by an ambulance was significantly greater among horses in the noncatastrophic group, compared with that of horses in the catastrophic group.
The proportions of horses with racing injuries positioned in the fourth (last) quartile of the group of horses competing in the race (field) and in the third and fourth quartiles (last half) of the field at a point one quarter of a mile after the start (first quarter fraction) were significantly greater than was expected by chance alone. The proportion of horses with catastrophic injuries positioned in the last half of the field at the first quarter fraction was significantly greater than was expected by chance alone.
The forelimbs were involved in 90.2% of racing injuries. The suspensory apparatus of the forelimbs (sesamoid and interosseous ligament) was the area most frequently involved (44.7%), and 85.8% of all racing injuries were located from the carpus to the metacarpophalangeal joint.
Ninety-six horses’ injuries involved only 1 forelimb (81.8%). The proportion of horses (n = 96) with injuries that developed at or near the finish line was significantly greater for the right forelimb than for the left forelimb. Injuries of the left forelimb that developed in the stretch turn were significantly more common, compared with those of the right forelimb.
The proportion of horses with injuries involving the sesamoid was significantly greater for the left forelimb than for the right forelimb. The proportion of horses with injuries to the diaphysis of the third metacarpal bone was significantly greater among horses with injuries that developed in the backstretch and the turn ahead of the finish (clubhouse turn) than that for horses injured at other locations on the track. Injuries of the sesamoids were significantly more common in the stretch turn than at other locations on the track. Injuries of the third metacarpal condyle were significantly more likely to be detected after the race than during the race.