09/23/2019
More insight on the keratoma removal from a few weeks ago.
On 9/9/19, I was called in to remove the keratoma with assistance from farriers Richard Armentrout, Aaron Hill, Conrad Smoker and veterinarian Gabe Middleton, DVM from Orrville Veterinary Clinic.
A keratoma is a rare, benign tumor of the keratin or horn-producing cells. It is a firm, nodular, yellow-grey mass. If anything alters the normal pathways controlling the activity of the dividing cells, it may result in a constantly increasing mass of abnormal tissue, with a keratin core, between the outer hoof capsule and the pedal bone. Although it is thought that chronic irritation may make the horse prone to the condition, many horses diagnosed with keratomas have no history of either infection nor injury at the site. Any size, breed or gender of horse may succumb to the problem. Some horses may remain sound, but they generally show a mild, intermittent lameness that gets gradually worse. The only indication of a keratoma may be an abnormality of the contour of the sole or wall noticed during routine farriery and toe cranea notch. Keratomas of the wall tend to originate from the coronary band and can cause bulging and distortion of the wall, which is visible externally. Keratomas of the sole are generally circular and their size can vary from 0.5-2cm in diameter. In either case, widening of the white line with dense rubbery white tissue is frequently apparent. The first signs to look for are the characteristic changes in contour of the wall and sole, and an abnormal area of the white line. Radiographs can then be used to examine the mass and any damage to the underlying pedal bone. This happens if the mass has exerted sufficient pressure to cause absorption of the bone. The result is a smooth bordered semicircular defect in the bone. Treatment of a keratoma is based on removal of the abnormal tissue, but is often easier said than done. The appropriate section of the outer hoof wall must be removed to allow access to the underlying keratoma. Depending on the position and extent of the keratoma, this may be achieved with the horse standing under sedation, with local anaesthetic blocks to numb the foot pain. Otherwise a general anaesthetic will be required. In either case, it is essential to ensure removal of all abnormal tissue — especially if it goes as far as the coronary band — otherwise the keratoma will keep growing. A commonly used surgical technique involves making two parallel cuts either side of the keratoma, from the sole up the wall as far as is necessary, to ensure the whole of the mass is removed. The wall is then removed by pulling it up and effectively “unpeeling” the hoof wall from the bottom of the hoof to above the tumour. The tumour can then be completely removed. I’m not in favor of this technique due to the excessive amounts of hoof wall removed. I prefer to use a Forstner bit larger than the keratoma and drill a hole and remove the keratoma through it. Most horses recover well from keratomas, as long as the entire tumour is removed. Prognosis is good if all the abnormal tissue is removed. Incomplete removal equals re-growth. Removal is generally done standing and under general anesthesia. Radiographs are used to determine exact drilling spot. Removal is by partial or complete resection. 6 to 12 months recovery is expected. In this case, only the lright hind foot had a keratoma. The attending farrier (Conrad), trimmed and shod the hoof before the keratoma removal. The veterinarian provided a mild sedation while I went to work removing the keratoma. After treatment is cleaning of the area, packing with a gauze pad soaked in mild betadine solution and a piece of duct tape over are to hold gauze in.
