Effect of horse breed and sex on growth rate and radiographic closure time of distal radial metaphyseal growth plate

The aim of this study was to estimate the effect of breed and sex on the growth rate and the radiographic closure time of distal radial metaphyseal growth plate of horses of different breeds. The study used 81 animals comprising Thoroughbred (10 colts and 9 fillies), Arabian (10 colts and 10 fillies), Anglo-Arabian (10 colts and 11 fillies) and Hucul (10 colts and 11 fillies) breeds. On the basis of biometrical data the growth rate was estimated from birth to 20 months of age for each animal. To determine the time to radiographic closure of the distal radial metaphyseal growth plate radiographs of the left carpus of each animal were performed at 20 months and thereafter once monthly until growth plate closure. Thoroughbred and Arabian breeds exhibited significantly greater growth rate between birth and 20 months of age in comparison to Anglo-Arabians and Huculs. The earliest time of metaphyseal growth plate closure was achieved by Arabian horses (mean 718.1 days) and was significantly earlier than Hucul (mean 794.1 days) and Anglo-Arabian (mean 810.1 days) breeds. Mean time of growth plate closure of Thoroughbred horses (mean 756.3 days) was significantly shorter than in Anglo-Arabians. Within each breed metaphyseal growth plate closed earlier in fillies than in colts but only in Thoroughbreds the statistical differences were significant.