Keratoma – foot tumor

The horse’s foot is a complicated structure and we’ve all heard of the saying “no foot, no horse” – well this is true of keratomas. They should be treated as an emergency and prompt treatment is essential for a successful outcome and future athletic soundness.

A keratoma is the formation of abnormal tissue (a benign tumour/cancer) within the inner layers of the hoof wall of the horses foot. Keratomas are benign, therefore they do not spread to other parts of the horses body.

Keratomas tend to originate from the coronary band and grow downwards toward the toe and can extend to the solar surface of foot at the white line. Very occasionally they can originate further down the hoof wall or from the sole.

They are usually found at the toe, or occasionally quarter, of the foot from coronary band to sole or anywhere in between.

The exact cause is unknown, but some cases are thought to be caused by chronic irritation of the internal laminae of the foot as a result of injury or infection. Injury to, or inflammation of, the coronary band is also thought to be a possible cause.

Sometimes there are no visible signs on the outside of the hoof that a keratoma is present, lameness may be the first sign. However, bulging of the hoof wall at the coronary band is commonly seen. Lameness will develop depending on the size, position and speed of growth of the keratoma, therefore it may appear as sudden onset, progressive or intermittent lameness.

Your vet will examine your horses foot for any other signs such as distortion of the white line or white line separation. Pus may also be seen at the white line or coronary band. Your horse will also show signs of pain when hoof testers are used over the affected area.

Your vet will also take x-rays of your horses foot to identify exactly where the keratoma is, this will also show how advanced it is. The keratoma will show up as a dark area on the pedal bone where the bone has become damaged. MRI may also be used for more complicated cases.

A biopsy of the affected tissue can also be taken and tested for a precise confirmation of diagnosis.

Surgery is usually required to remove a keratoma.

If there are any sites of discharge then this can be encouraged to drain by careful debridement of the surrounding horn, and poulticing, soaking or lavage may help in the short-term before surgical resection is performed.

During surgical removal the hoof wall is cut and taken out over the area of the keratoma so it can be removed. The wound is then packed with gauze soaked in povidone-iodine solution (an antiseptic agent) and a hospital plate will be fitted to the shoe to protect the area, the foot is then bandaged to prevent any dirt from entering the wound. Your vet will administer antibiotics to prevent infection.

Your horse will have to remain on box rest and the wound will need to be checked and re-dressed every 2-3 days until a hard layer of horn has formed over the area. When the hospital plate and bandaging are no longer needed your horse will be fitted with a shoe appropriate for the type of wound in order to stabilise the defect in the hoof wall. Following this the horse will have to remain in clean, dry conditions until the wound has completely healed over.

The hoof wall grows at a rate of approximately 0.6 cm each month, therefore complete re-growth of the hoof wall defect can take many months. But with patience and careful management the prognosis is usually good.

If complete removal of the keratoma wasn’t achieved, recurrence is likely and further surgery will be necessary.

Because the cause of keratomas isn’t fully understood, methods of prevention are unknown. However, if your horse sustains an injury to the coronary band or you notice inflammation in that area this should be investigated immediately and treated promptly.