Description

Corns are traumatic injuries that result in hemorrhage into the sensitive tissues of the sole at the angle of the sole between the hoof wall and the bars in the horse's hoof. This site is the seat of the corn. The hemorrhage increases pressure in the sensitive tissues of the medial (inside) aspect of the front feet, resulting in pain and lameness.

The hemorrhage causes discoloration, which appears as a typical bruise. Corns may develop suddenly or over a longer period of time. Chronic corns occur most often in horses with low heels. When the walls collapse inward, they injure the seat of the corn.

Moist corns occur when the trauma causes fluids to accumulate under the sole, giving the impression that the horn of the sole is wet.

Dry corns cause thinning of the sole over the seat of the corn. If the sole is pared away with a hoof knife, a red bruise will likely appear.

When infection develops underneath the sole at the seat of the corn resulting in pus formation, the corns are referred to as 'suppurating corns.'

Symptoms

• Lameness with a shortened stride favoring the heels
• A pain response upon application of hoof testers over the seat of the corn
• Increased digital pulse strength
• Feet may feel warm to the touch
• Blood streaked horn or pus may be found when shoe is removed
• Hoof wall may be curled under at the heel

Causes

Corns are nearly always caused by shoes that do not fit properly. In most cases, they are too short and tight at the heels, causing injury in the seat of the corn. Shoes that are left on too long can have the same effect. As the foot grows, the shoe is carried forward, causing the heel branches to traumatize the seat of the corn.

In other cases, excessive weight bearing at the heels, where heel caulks or studs have been used may bruise the seat of the corn. Stones that become lodged between the shoe and the seat of the corn can also cause trauma and bruising.

Prevention

Careful attention to proper shoeing is the best prevention. Inspecting the horse's hoofs and shoes on a regular basis will help prevent corns caused by stones or debris at the seat of the corn. Shoes should be fitted long and full at the heels to support the heels and encourage growth.

Regular hoof trimming by a competent farrier is the best way to prevent corns in horses. By avoiding excessive foot trauma on hard ground, maintaining proper shoeing, and paying attention to any signs of lameness, corns can be prevented in most horses.

Treatment

The horse's shoes should be removed as a first step. Dry and moist corns are pared with a hoof knife to relieve pressure. Suppurating corns should be opened to drain, and packed with an antiseptic-soaked cotton wool plug. Antibiotics such as penicillin are useful once the area is draining freely, and, if needed, a tetanus shot should be given. The shoes should be left off until the area is healed. A palmar digital nerve block may be given to treat lameness.

Leather or polypropylene pads are useful in preventing further injury if it is necessary to reshoe the horse before that area is completely healed. Bar shoes can be used to prevent further bruising.

Shoes need to be fitted properly to prevent shoe pressure on the white line or on the seat of the corn. The heel may need to be cut down to sound tissue and the horse shod with raised, graduated heels to balance the foot and maintain correct alignment. Plastic heel wedges may be used to retain foot level and balance, but care should be taken to make sure they do not aggravate the problem.