Radiographic assessment of proximal sesamoid bones in suckling and yearling Thoroughbred horses and its correlation to racing performance

Abstract

Radiographic abnormalities are often observed in athletic horses and they can interfere with the performance of racehorses. The origin of changes in sesamoid bones, as well as their evolution or involution during animal growth, remain unknown. The aims of the present study are to radiographically assess proximal sesamoid bones in Thoroughbred horses at suckling and yearling stages, in Curitiba, Paraná, Brazil, as well as to investigate the influence of radiographic changes in these bones on animals’ sporting performance. In total, 86 animals were investigated at suckling and yearling stages, in 2012, based on the following radiographic projections: back 15º proximal-palmarodistal oblique, lateromedial, back 30^o medial-palmaro/plantarolateral oblique and back 30^o lateral-palmarolateral/plantarolateral oblique. Radiographic changes observed in animals’ sesamoid bones were scored from 0 to 4. The number of races and horses’ performance were classified based on a previously proposed score, by taking into consideration the official results of races held at hippodromes, which were obtained at the end of the study. Healthy horses without bone-related changes were attributed scores 0 and 1, whereas horses presenting bone-related changes were attributed scores 2, 3 and 4. Statistical analysis was based on Wilcoxon and Mann-Whitney tests, at 5% significance level (p < 0.05). Radiographic changes were identified in 3.6% of 688 sesamoid bones analyzed at suckling stage and in 3.7% of bones analyzed at yearling stage. There was significant increase in the number of lateral sesamoid bones with abnormalities in animals’ thoracic and pelvic limbs, from the suckling to the yearling stage. The current findings have evidenced that radiographic changes in proximal sesamoid bones of Thoroughbred racehorses take place at suckling stage and that changes observed at yearling stage did not affect the number of races or animals’ performance.