One of the leading causes of involuntary culling of breeding stock in swine is lameness. Many of these sows are lame due to lesions of the hoof wall. Although an important function of the porcine hoof capsule is to protect the terminal limb structures, little is known about its anatomy. The purpose of this study was to create a basic reference for normal porcine hoof measurements as well as quantify the density of epidermal laminae.

For the hoof wall measurements, forty forelimbs and forty hind limbs were obtained from clinically sound sows and sixty-nine forelimbs and seventy-four hind limbs were obtained for the second part of the study. For the hoof wall, measurements were made investigating the dorsal wall length, abaxial wall height, sole width, sole + wall length, ground surface, dorsal wall depth, abaxial wall depth and the sole depth at the cranial, caudal, axial and abaxial aspects. The second group of limbs were sliced for visualization of the laminar junction. The laminae were stained and divided into zones of 25 laminae each.

Significant differences were present between the dorsal wall depth and the abaxial wall depth of various digits, but the sole depth at all four measurements (cranial, caudal, axial, abaxial) was significantly thicker than the abaxial wall depth on all eight measured digits (p<0.0001). The laminae also showed significant decreases in zone width as they moved from the palmar/plantar aspect of the hoof to the dorsal aspect with zones A and B being significantly smaller than all of the other zones on both the thoracic and pelvic limb (p<0.0001).

These results demonstrate that the thinnest measured location of the hoof wall is the abaxial wall. The abaxial wall wall depth is significantly less than the depth of the hoof at the location of the sole, or in many digits, the dorsal wall as well. The abaxial wall region also holds the least dense zones of epidermal laminae, with the density increasing at the more dorsal aspect. With the thinnest wall and the sparsest laminae, the inherent anatomy of this region is likely to play a role in the frequency of lesions reported in this location.