82 Relationships between performance traits and osteochondrosis of the hock in Standardbred racehorses

Abstract Equine osteochondrosis (OC) is a developmental orthopedic disease that results in abnormal articular cartilage and often the formation of osteochondral bone chips (osteochondrosis dissecans). Standardbreds, a breed predominately used in harness racing, are prone to the development of OC. This study aimed to quantify the relationship between OC and key performance traits, fastest mile time, annual earnings, and consistency in race times over career, using a cohort of 347 North American Standardbred horses. Radiographic examination of the tarsi was previously performed to identify horses as OC-affected (n = 155) or healthy (n = 192). Performance data was acquired from the United States Trotting Association (USTA) detailing horse identification, performance, and lifetime race record. Linear mixed multiple regression models were constructed to evaluate the relationship between OC and performance. A total of 24 performance related variables (e.g., age, gait, track) were evaluated for inclusion in the model through subset variable selection and goodness of fit as determined by Schwarz’s Bayesian Information Criterion (SBC). Preliminary results indicate that healthy horses exhibit significantly faster mile times (P < 0.001) compared with their OC-affected counterparts. However, no significant association was detected between OC status and annual earnings (P > 0.2) or consistency in race times over career (P > 0.2). Ongoing analyses are currently being conducted to assess additional predictors and performance variables for a potential association with osteochondrosis. This study emphasizes the importance of implementing effective strategies for OC management and improving breeding selection practices when producing offspring with desired performance characteristics.