BONE SPAVIN
Black Hawk’s left hock (B) shows no pathology. In contrast, a left hock (A) of an anonymous museum specimen shows the characteristic appearance of “bone spavin” on the front, rear and lateral aspects of the limb at the base of the hock joint. At the front of the joint (top) the deep ligament fibers (red arrow) have mummified but are otherwise normal. In the rear view of this joint, the pocketlike facets are for the first tarsal bone, which was partially fused with the pancake-like second and third tarsal bones; it has broken off postmortem from the area indicated (yellow arrow). These bones fuse in half of all domestic horses, so the degree of spavin pathology here is low. Nonetheless the ossification of the deep ligament fibers surrounding this joint is clear (blue arrow). There is no evidence of bone spavin in Ethan Allen’s hocks; seen here are the first tarsal bone (A), the top surface of hind cannon bone (B) and a rear view of the hind cannon bone (C).