Flexural properties of the equine hoof wall

Abstract

The equine hoof wall is a hard keratinous structure which transmits forces generated when the hoof contacts the ground to the skeleton of the horse. During locomotion, the hoof capsule is known to yield under impact resulting in an inward curvature of the dorsal wall and expansion of the heels. However, whilst researchers have studied the tensile and compressive properties of the hoof wall, there is a lack of data on the flexural properties in different locations around the hoof capsule. In this study the flexural properties and hydration status of the hoof wall was investigated, in two orthogonal directions, in different locations around the hoof capsule. The hoof was divided into three regions: the dorsal-most aspect (toe); the medial and lateral regions (quarters) and the heels caudally. Beams were cut both perpendicular and parallel to the axis of the tubules, termed transverse and longitudinal beams respectively. Differences in the mechanical properties were then investigated using three-point bending tests. There were considerable differences in the mechanical properties around the hoof capsule; transverse beams from the toe were 81% stiffer and 28% stronger than those from the heels. This corresponded with differences in the hydration of the hoof wall; beams from the toe had a lower water content (24.1±0.25%) than those from the heels (28.3±0.37%). Differences in the flexural properties are thought to be largely a result of variation in the water content. Mechanical data are further discussed in relation to variation in the structure and loading of the hoof wall.