Laminar Variation and the Hoof Wall

A postmortem survey was conducted with the front feet from 25 Thoroughbred cadavers, horses that were euthanized for reasons unrelated to the musculoskeletal system.

The goal was to describe variation in the microscopic appearance of the laminar junction and thickness of the hoof wall at several locations around the hoof wall from below the coronary band to the ground surface. Orientation of the lamina in relation to the hoof wall, degree of bending and spaces between the laminae were measured. The thickness of the hoof wall and number of branched primary epidermal lamina were also recorded.

There were significant differences in laminar orientation and bending between proximal and distance sites. Toe regions were also significantly different from heel regions. At the toe the laminae were mostly straight or slightly curved, but the curvature increased toward the heels. The stratum medium and lemellatum were thicker at the toe and decreased toward the heels, with the hoof wall thicker laterally than medially. The highest numbers of branched laminae were found at the toe and quarters. There were more branched laminae on the lateral side of left hooves and medial side of right hooves.

The authors conclude these data are evidence of adaptive remodeling of the laminar junction. Several horses were in race training. The authors suggest some results may be adaptive remodeling in response to applied stress from counterclockwise training in the U.S. The results also show that while most primary laminae are produced at the…