Abstract
The forelimb fetlock joint and its bony components are a common site of injury in racing horses. We hypothesized that the variations in relative density of these bones might correspond to their mechanical properties. This study aimed first to identify the relative density of third metacarpal bone (Mc3), proximal phalanx (P1) and proximal sesamoid bones (PSBs) of Thoroughbred race horses. Second, to determine whether there was any difference and/or similarity in the relative density between and within the bones. Bones from right and left forelimbs of 10 horses were collected and prepared by boiling and drying. Dry weight and volume for each bone were measured and the relative density was then calculated. Relative density of Mc3 was substantially greater than the other two bones with a mean of 1.7 ± 0.06. Relative density of P1 and PSBs showed a high similarity especially between P1 and the medial PSBs. Neither the comparisons between right and left sides nor between lateral and medial PSBs showed any significant differences. P1 had the most consistent relative density within right and left sides. Larger relative density in Mc3 and the similarity between P1 and PSBs presume a more important role of the bone mass on their properties than the volume.