Equine Foot Ailments EQS 200 – Lameness in Racehorses

The equine foot consists of the hoof as well as all the bones, blood vessels, ligaments, tendons and nerves within. The hoof is divided into three regions: the toe, the quarters and the heel. Functions of the Hoof provide a weight bearing surface protect the internal structures of the foot provide traction shock absorption The bones within the equine foot are the coffin bone, navicular bone and distal end of the short pastern.

The solar surface of the hoof consists of the heel bulbs, frog, sole, white line and bearing edge of the hoof wall. The heel bulbs are formed by the back of the digital cushion, which is the main shock absorber of the hoof. The white line is the junction between the laminae of the wall and the sole.

The Thoroughbred has been bred for speed and efficient use of energy. As a result the Thoroughbred’s foot tends to have a thin hoof wall and sole making it more susceptible to trauma, injury and hoof capsule distortion. Equine hoof imbalance and distortion affect function and have a direct correlation with musculoskeletal injuries and lameness. Photo: Big Brown (note front hooves – quarter cracks repair). Hoof capsule distortion refers to imbalanced hooves such as flares, cracks, sheared heels, etc. The most common imbalance are feet shod with too much toe length and inadequate heel length. The center of the shoe’s weight bearing surface should line up with the center of the coffin joint (widest part of the sole).

Racehorses are generally kept in a stall for 22 hours or more per day. Hoof capsule distortions occur slowly over time and result from long-term abnormal weight bearing. When exercising, the track surface packs into the sole and provides support. Most distortions of the equine hoof occur while the foot is semi-static. Racehorses are generally kept in a stall for 22 hours or more per day. It is extremely important to provide sole support to the stalled horse!!

Common Ailments of the Equine Hoof

Thrush Thrush is a common anaerobic bacterial infection of the hoof tissue characterized by a black, necrotic, foul-smelling residue. Thrush typically affects the central and collateral sulci and does not cause lameness but in severe cases it can also invade the white line, sole and sensitive layers of the foot.

Cause… Neglect of Daily Hoof Care (especially in wet, unhygienic conditions) Inadequate Trimming (promotes contracted heels and deep sulci) Insufficient Exercise is the #1 cause of Thrush Insufficient Exercise

Treatment / Prevention Successful management of thrush includes: trimming away dead, infected tissue application of medication stimulation of the frog with regular exercise Daily management and regular turnout / exercise is the most effective method to prevent thrush!!

Hoof imbalance is a major cause of hoof wall cracks. Toe, Quarter & Heel Cracks A crack represents a failure of the hoof wall and can occur anywhere in the hoof. Hoof imbalance is a major cause of hoof wall cracks. Environmental, genetic, nutritional, and conformational factors also play an important role in hoof health and strength. Daily inspection as well as keeping the horse on a regular trimming / shoeing schedule, can help prevent hoof cracks from developing.

deep (involves the underlying sensitive structures / laminae) A hoof wall crack can be… superficial (only involves the hoof wall) deep (involves the underlying sensitive structures / laminae)

Lameness is not typically present with superficial cracks, but a deep crack can cause lameness due to the pressure on the underlying laminae. A deep crack can also cause secondary infection from exposure of the sensitive tissue to environmental bacteria. The hoof wall around the crack is usually sensitive to hoof testers with infected hoof cracks and those that are contributing to lameness.

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