Keratoma

• keratoma = Hyperplastic keratin mass within the hoof
• a keratoma originates from the epidermal horn producing cells of coronary band. This may be a benign neoplasm that grows distally (from the germinal cells in the coronary band) towards the toe with the hoof. This acts as a space occupying lesion within the hoof capsule leading to…

  • Pressure necrosis in adjacent distal phalanx
  • Hoof deformation
  • Loss of white line integrity allows entry of bacteria which can then cause a hoof abscess
• A keratoma is most common in the toe region of the hoof (but can also be seen on the side) and may occur following an insult to the germinal cells at the coronary band e.g., hoof abscess, trauma or a hoof crack propagating upwards. Cases may have mild intermittent long term lameness but they usually have recurrent severe lameness. Other signs include…

  • Recurrent hoof abscesses at the same location
  • Raised digital pulse (single foot)
  • Possible hoof wall distortion
  • Deviation of white line with a flexible ‘Cork like’ growth visible
  • Localised pain with hoof testers
  • Drainage from abscess
• The lameness is abolished by peri-neural anaesthesia (abaxial or higher to numb the dorsal structures) of the foot. Diagnosis is confirmed with radiography ideally use a dorso60°proximal –palmar/plantar distal oblique view (upright pedal) where a smoothly demarcated radiolucent lesion in the distal border of distal phalanx
• Treatment involves a partial hoof wall resection from the dorsal hoof wall. This is done under GA with perineural anaesthesia. An oscillating saw is used to cut a window through the hoof in the region where the keratoma is thought to be (this is decided via the distortion in the white line and radiography). A bridge of hoof wall is left at the bottom and top to allow for stability in the hoof. Once a full thickness cut has been made, osteotomes are placed under the wedge to leaver it out.
• Aftercare involves hydro gel in the wound to stimulate granulation, gauze swab and bandages. Once a granulation bed has been formed, the hydrogel is replaced with iodine and as weeks pass the bandaging can be removed. The bridge of hoof left at the top grows down creating a new healthy hoof wall. A keratoma takes several months for hoof defect to grow out but otherwise has a good prognosis.