Keratomas in Horses

Keratomas are a rare type of tumor that develop in the hoof of the horse, potentially causing pain and lameness and preventing them from walking properly. These tumors are benign and do not spread to other parts of the body. Prompt veterinary attention is required for horses that are lame and have repeated abscesses in the hoof or bulging hoof walls.

There does not appear to be any predisposition to this condition based on gender, age, breed, or lifestyle.

The severity of a keratoma depends on how quickly it grows and its position within the hoof.

Some keratomas seem to lame a horse very suddenly, while others cause subtle changes to the gait over time.

In some cases, the keratoma grows down to the white line, causing pain and a separation in the white line (the inner layer of the wall).

In cases where a bacterial infection occurs, pus may be present.

In rare cases, two or more keratomas are present in the same hoof.

The cause of keratomas is not yet fully understood, although some appear to be the result of injury to or inflammation of the coronary band (also known as the coronet - the part of the hoof responsible for growing new hoof horn). Keratomas develop from the horn producing cells and contain large amounts of keratin. They grow downwards towards the sole, eventually leading to separation of the hoof wall from the sole at the white line. The space created by this separation is vulnerable to bacterial infection. The bacterial infections tend to lead to repeated hoof abscesses, which is typically how the owner is alerted to the keratoma.

In addition to bulging of the hoof wall, distortion in the white line of the hoof, and separation or increased size of the white line is also observed.

Horses that are experiencing lameness, especially alongside abscesses in the foot or bulging in the hoof wall, require prompt veterinary attention.

Diagnosis is based on physical examination, lameness examination tests, and X-rays.

Keratomas require surgical removal. In some cases, these require general anesthetic. In others, only a local anesthetic and standing sedation is necessary. Once removed, the tumor is submitted for analysis to ensure it is benign.

Post- operative care of the hoof is required for several months after the surgery, until the hoof wall regrows to cover the surgical site and a thin layer of horn develops that will protect the foot.

This care includes:

• Antibiotics
• Wound dressings changed regularly
• Special shoeing to stabilize the weakened hoof
• Providing a clean, dry environment

Once the horn layer forms, the remaining defect in the hoof can be filled with synthetic resin to provide stability. The defect will grow out completely within a year.

The prognosis for a full return to soundness is excellent with treatment and extensive, careful management. The hoof often closes enough to allow for resin filling of the defect within 8 to 12 weeks. Horses with a resin filling can undergo light exercise or riding, as long as they are not lame. The defect grows out completely within a year.

There are no known preventative measures for keratomas.

Keratomas are uncommon in horses.

• Surgery