Lameness caused by foot problems is common in the horse, and it can significantly impact how well a horse can perform. Hoof bruising, heel soreness, hoof cracks all create discomfort that alter a horse’s gait and prevent him from giving his utmost to an athletic task. Nearly all equine foot diseases have their root in biomechanics, noted a University of Georgia veterinarian at a recent in-depth podiatry seminar, and veterinarians and farriers must take a biomechanical approach to treating these problems.

Andrew Parks, MA, VetMB, MRCVS, Dipl. ACVS, professor of Large Animal Medicine at the University of Georgia’s School of Veterinary Medicine reviewed important elements of equine foot anatomy during the session, which was held during the 2012 American Association of Equine Practitioners’ Convention, held Dec. 1-5 in Anaheim, Calif.

Parks started with a bit of biomechanical anatomy review: While the long bones of the skeletal system, such as the radius (forearm) or the cannon bone, effectively transmit force from one end to the other, the distal phalanx (coffin bone, a short bone) , acts as a shock absorber, transferring weight-bearing forces from the hoof to the skeletal system. This bone is also well-adapted for attachment to soft tissues (tendons and ligaments) that aid or resist movement. “The principle forces acting on the foot are the weight of the horse, the ground reaction force (GRF), and the tension in the deep digital flexor tendon (DDFT, which runs from the underside of the coffin bone to the flexor muscles higher in the leg),” he explained.

The GRF matches the weight the limb bears, but it is exerted in the opposite direction. When a horse’s foot stands on a flat, firm surface, the GRF distributes around the perimeter of the hoof capsule. But when standing on a conformable surface such as sand, the GRF distributes broadly across the bottom of the horse’s foot. In both cases GRF pressure is greatest approximately in the center of the foot, just in front of the coffin joint