Developmental orthopaedic lesions are commonly found in French Standardbred horses. One of the main questions asked by trainers, owners and veterinarians is what impact these lesions have on the racing career and racing performances of horses.
To study the prevalence and distribution of developmental orthopaedic lesions in young French Standardbred trotters and to relate them to racing performance.
Feet, fetlock, tarsus and stifle regions were radiographed in 865 two-year-old French Standardbred trotters. Abnormal radiographic findings (ARF) were evaluated for 12 anatomical sites identified in these areas, and a severity index given. Performance criteria were: success in qualification for racing, maximal and mean index of trot (ITR), an annual index calculated on the basis of the logarithm of earnings per starts, total earnings at 5 years, placed races compared to starts and longevity of the racing career. Analysis of variance were calculated to study the relationships between racing performance and the number of ARF or the severity index.
A total of 363 horses (42.0%) showed ARF. Prevalence of ARF was 18.3% in the plantar aspect of the hind fetlock and 10.6% in the proximal tarsus. Among the total population, 833 horses were considered for performance evaluation, 478 of them were qualified for racing. The number of ARF significantly affected racing longevity. However, the number of ARF did not affect performance categories according to maximal ITR. Concerning distribution of ARF, the number of plantar lesions in the fetlock significantly affected mean ITR. The index of severity did not provide more information for prognosis than the number of ARF.
Longevity is the only criteria affected by ARF. When evaluating different sites, only the plantar fetlock region showed a significant relationship with mean ITR.
Number of ARF and radiographic score (RS) affect mean ITR and longevity but do not affect maximal ITR. A horse with a good racing ability will be a good performer but might have a racing career shortened because of orthopaedic problems in relation to developmental orthopaedic lesions.