After removal of the hoof cast, the bone cement plaque is checked for stability and any amount of drainage. If there are no signs of complications, an acrylic patch is applied over the bone cement plaque and a bar shoe with two clips is used to provide increased stability of the hoof capsule. In cases where the defect is more distal in the hoof capsule a glue-on shoe with a full plate (Sigafoos, Series II, cuff and plate) can be used if a traditional shoe cannot be applied. The hoof wall defect including the bone cement plaque and the acrylic patch will grow down during the following months and can be trimmed as needed until fully grown out. Ridden flatwork can be initiated as soon as the acrylic patch is in place and the horse is sound, which, in an uncomplicated case, is typically around 4 to 6 weeks postoperatively.
A keratoma can be columnar or spherical in shape. As it enlarges over time the resulting pressure on the third phalanx can lead to bone resorption. The underlying cause of keratomas is suspected to be focal trauma or inflammation. Keratomas have also been reported to develop as a consequence of hoof abscesses.
Keratomas can cause lameness due to focal pressure and inflammation of the sensitive lamina and underlying coffin bone. In some cases, they may be incidental findings when obtaining routine foot films. The poor hoof quality which can develop due to the presence of a keratoma will facilitate colonization by bacteria or fungi further weakening the hoof horn. These changes then contribute to recurrent hoof abscesses at the same site. In general, they are relatively rare and therefore may be overlooked.
If a columnar shaped keratoma has grown distally to reach the solar surface of the hoof, it can be recognized by a round area of reduced horn quality at the white line where lamellar horn is replaced by tubular horn and scar tissue. Spherical keratomas can be found at any location of the hoof wall and may not be apparent when inspecting the white line of the sole. Depending on the chronicity, radiographs may show a round bone defect in P3 with a smooth, sclerotic border.
Differential diagnoses that should be considered are septic osteitis of the third phalanx, white line disease, and traditional hoof abscesses.
If radiography is inconclusive, computed tomography or magnetic resonance imaging can provide a definitive diagnosis. Advanced imaging will provide valuable information about the size and location of the keratoma to facilitate surgical planning. This allows for a more targeted approach and use of a partial hoof wall resection as opposed to the originally described more radical debridement. Traditionally, a complete hoof wall resection was the treatment of choice which could result in an unstable hoof capsule and chronic lameness as well as a prolonged postoperative healing period. Mapping the keratoma via computed tomography allows for a targeted partial hoof wall resection while still allowing the complete removal of the keratoma. The more limited partial hoof wall resection will also allow for a shorter convalescent period providing a much earlier return to exercise.
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