Postoperative racing performance in standardbreds and thoroughbreds with osteochondrosis of the tarsocrural joint: 109 cases (1984-1990).

This research study reviews the racing performance of Standardbred and Thoroughbred horses with the joint disorder, Osteochondrosis dissecans (OCD). The study concluded that the horses, treated for OCD through arthroscopic surgery before their racing age, showed a competitive racing performance when compared to their siblings who were not affected by this disorder.

Research Methodology

• The study involved 109 horses – 64 Thoroughbreds and 45 Standardbreds – diagnosed with OCD of the tarsocrural joint. These horses underwent arthroscopic surgery to remove the fragments caused by the disorder, before they turned two years old and before they started racing.
• The location of the lesions was recorded for all subjects of the study.
• For a comparison, the siblings of the horses treated surgically were identified using the mare progeny records. Information on these horses, not suffering from the disorder, became the base data to compare the racing performance.

Data Collection and Analysis

• The study gathered racing data for two racing years – when the horses were 2 and 3 years old. The number of races they ran and the money won in these races was recorded.
• The data was obtained from the Jockey Club and the United States Trotting Association, for both the treated horses and their siblings.
• A statistical analysis was performed to test the hypothesis that the racing performance of horses with OCD, treated surgically before racing, was the same as their siblings without the disorder.

Results

• The study recorded 174 lesions in 109 horses. The distribution of lesions was similar to previous reports.
• From the Standardbreds, 22% of those treated with surgery raced when they were 2 years old; this figure rose to 43% when the horses were 3 years old. This is in comparison with their siblings, where 42% raced when 2 years and 50% raced as 3-year-olds.
• Of the Thoroughbreds that went through surgery, 43% raced as 2-year-olds and 78% raced as 3-year-olds. For their siblings without the disorder, 48% raced as 2-year-olds and 73% raced as 3-year-olds.

The study provides evidence that horses treated for OCD before they begin racing can perform competitively, when they are compared to their siblings not affected by the disorder.