Stress fractures of the vertebral lamina and pelvis in Thoroughbred racehorses.

This research studied 36 Thoroughbred racehorses that died on California tracks, finding significant evidence of stress fractures in the spine and pelvis, suggesting these issues could be a major cause of poor performance and lameness in these animals.

Research Methodology

• The study focused on 36 Thoroughbred racehorses which were evaluated posthumously between October 1993 and July 1994.
• The lumbosacral spine and pelvic areas of these horses were collected, cleaned of soft tissues, and visually inspected for signs of stress fractures.
• The researchers looked for an incomplete fracture line and localized new bone growth, which are distinctive features of stress fractures.

Key Findings

• The results showed that 61% of the examined specimens had evidence of stress fractures in the caudal section of the thoracic and lumbosacral regions of the spine, as well as the pelvis.
• Stress fractures in the vertebral laminae were found in 50% of the examined specimens. These fractures were linked with the severity of dorsal spinous process impingement, and the overall severity of degenerative changes in the articular process.
• 28% of specimens were found to have pelvic stress fractures. These were observed more frequently in older horses, and were associated with the severity of impingement in the lumbar transverse process, among other degenerative changes on the ilial articular surface.

Implications and Conclusions

• The research found a high incidence of stress fractures of the vertebrae and pelvis among the sampled Thoroughbred racehorses, who had died from unrelated causes.
• The study highlights the necessity to consider vertebral and pelvic stress fractures in clinical evaluations of horses presenting with signs of hindlimb weakness or back issues.
• The research suggests that undiagnosed stress fractures in the vertebrae or pelvis could be significant contributing factors to poor performance and lameness in Thoroughbred racehorses.