Caudal lumbar vertebral fractures in California Quarter Horse and Thoroughbred racehorses.

The research studied the nature of lumbar vertebral fractures in Quarter Horse and Thoroughbred racehorses, particularly how they take place and any pre-existing conditions that could predispose the horses to such injuries. It found that these fractures usually occur in horses with existing anomalies at the L5-L6 vertebral junction, suggesting early detection may help prevent serious injuries to horses and associated risks to jockeys.

Objectives and Methods

• The primary objective of this study was to better understand the occurrence and causes of lumbar vertebral fractures in racehorses by analyzing data on these injuries in California.
• To meet this objective, the researchers carried out a retrospective review of post-mortem reports and jockey injury records.
• They also conducted a prospective case-control study involving detailed examinations of vertebral specimens from six affected racehorses and four control horses euthanized due to non-spinal fractures. These examinations involved visual, radiographic, computed tomography, and histological evaluations.

Findings

• Over a 22-year period, such fractures were documented in 38 Quarter Horses and 29 Thoroughbred horses, predominantly involving the 5th and/or 6th lumbar vertebrae.
• The research found that these fractures were the third most common musculoskeletal cause of death in Quarter Horses and frequently resulted in injuries to the jockeys.
• The study observed variations in the number of vertebrae, dorsal spinous processes, and intertransverse articulations in the lumbar vertebral specimens examined.
• In the six assessed case specimens, fractures followed a distinctive path from the front-bottom (cranioventral) to the rear-top (caudodorsal) direction across the L5-L6 vertebral endplates and the intervertebral discs. However, one case involved only a single endplate.
• All cases displayed abnormalities on the ventral aspect (the underside or belly side) of the vertebral bodies indicating pre-existing pathology.

Conclusions

• The study concluded that lumbar vertebral fractures typically occur in racehorses with pre-existing pathology at the junction of the 5th and 6th lumbar vertebrae (L5-L6).
• This identification offers critical information for early detection and management of such conditions, which could aid in preventing catastrophic injuries in racehorses and their associated jockeys.