Several studies have demonstrated a statistical association between management practices and juvenile osteochondral conditions (JOCC) in foals from birth to 6 months of age, but this association has not been investigated in yearlings. The purpose of the current study was to determine the adjusted effects of management practices on the onset and evolution of JOCC in French yearlings. The study sample consisted of 259 yearlings born on 20 stud farms in Normandy. The breeding conditions of these horses were monitored from 6 to 17 months. They were radiographed at 6 and 17 months to determine their radiographic score (RS) and its evolution. Potential risk factors were investigated using univariate and multivariate analyses. The prevalence of JOCC was 48% at 6 months and 42% at 17 months. Between 6 and 17 months, the RS changed (for better or worse) in 52% of yearlings.
The main risk factors leading to deterioration in the RS were traumatic. ‘Mixed housing’ during winter, pastures with rough ground and a bad RS at 6 months were significantly associated with deterioration in RS between 6 and 17 months. In the multivariate analysis, the breed was not significantly associated with any evolution in the yearlings’ RS.
This study provides some indications on protective measures to prevent the worsening of JOCC lesions between 6 and 17 months, a crucial period since it precedes the sale of yearlings and the beginning of training.