Prevalence, location and symmetry of noncatastrophic ligamentous suspensory apparatus lesions in California Thoroughbred racehorses, and association of these lesions with catastrophic injuries.

This research article explores the connection between ligamentous injuries in the suspensory apparatus (the network of ligaments in the horse’s leg that supports the animal’s weight and facilitates movement) of the Thoroughbred racehorses in California and the likelihood of these injuries leading to severe, sometimes fatal conditions. The researchers found that moderate damage to certain areas of these ligaments is common in racehorses and may increase the risk of catastrophic injuries or fractures.

Objective and Methodology

• The objective of this study was to understand whether lesions (wounds or injuries) within the suspensory ligament (SL) and distal ligaments of the proximal sesamoid bones (DSLs), important structures in a horse’s anatomy, are related to failures in the suspensory apparatus or fractures in the lateral condyle of the metacarpal bone (a bone in the lower fore limb of the horse).
• For the research, specimens from 327 deceased Thoroughbred racehorses were used. These were sectioned within the body of the SL and branches, as well as oblique and straight DSLs.
• Lesions that were purple and at least 2 mm in width were defined as moderate, while paler or smaller lesions were categorized as mild.
• A statistical approach (multivariable logistic regression) was then applied to assess any relationship between the occurrence of moderate lesions and factors such as the horse’s age, sex, the racetrack, and cause of death.

Findings

• The results showed that moderate lesions were found in 16% of the horse sample, whereas milder lesions were seen in 77% of the racehorses.
• Such moderate lesions were found to be similarly prevalent in the branches of the SL and in the oblique DSLs.
• These moderate lesions were also statistically more likely to occur in horses that had died from suspensory apparatus failure or metacarpal lateral condylar fracture, compared to those horses that died from non-musculoskeletal causes.
• Furthermore, older horses (aged 7 years or more) were more likely to have these moderate lesions compared to 2-year-old horses.

Conclusions

• The research concluded that moderate lesions in the suspensory apparatus ligaments are common among racehorses, particularly in the SL branches and oblique DSLs, and may potentially increase the risk of suspensory apparatus failure or fractures in the metacarpal condyles.
• Maintaining and monitoring the health of these ligamentous structures could be a practical way to assess fatigue in the forelimb suspensory apparatus and metacarpal condyles, possibly preventing severe injuries.