Correlation of racing performance with radiographic changes in the proximal sesamoid bones of 487 Thoroughbred yearlings.

This research studied the impact of proximal sesamoiditis, a bone condition, on the racing performance of Thoroughbred yearlings. The study discovered that abnormalities in the horse’s bones resulted in decreased performance and earning potential when they turned two and three years old.

Objective and Methodology

• The study aimed to ascertain the effects of proximal sesamoiditis – a common bone condition in Thoroughbred yearlings – on their racing performance over time.
• The researchers utilized survey radiographs of 487 Thoroughbred yearlings for the study.
• Their examination of the proximal sesamoid bones led to the categorization of findings into seven different categories: five relating to size, shape, and number of vascular canals, and two examining the radiographic shape of the sesamoid abaxial surface.

Findings

• Based on the yearling radiographs, vascular canals with parallel sides < 2mm in width were considered normal.
• Yearlings with one or two abnormally shaped vascular canals exhibited a significant decrease in racing starts at two years of age, as compared to horses with regularly shaped canals.
• Similar bone abnormalities in fore- or hindlimbs were associated with decreased starts and earnings at two years of age.
• However, if the abnormalities were consistently present in both fore- and hindlimbs, the horses’ performance was found to be comparable to that of normally structured horses.
• Yearlings with more than two irregular vascular canals demonstrated decreased racing starts and earnings at two and three years of age.
• In terms of the radiographic shape of the sesamoid abaxial surface, changes in proximal sesamoid bone contour didn’t affect the horses’ performance.

Conclusions

• The research concluded that yearling horses with larger than normal vascular canals in their sesamoid bones started fewer races and earned less prize money than horses with normal vascular canals.
• The impact of one or two enlarged vascular canals was especially seen when the horses were two years old.
• Three or more enlarged vascular canals negatively affected horses’ performance at both two and three years of age.
• Therefore, potential buyers should consider these results when examining radiographs of young Thoroughbred horses.