K E R AT OMA
Equine
keratoma
A keratoma is an uncommon, benign tumour originating from horn-producing
cells in the foot, typically starting under the coronary band and growing down
with the normal hoof. As they continue to grow, separation between the hoof
wall and sole can occur allowing bacteria to penetrate the foot. The result of
which is abscess development
.
Lee Pritchard BVSc MRCVS,
Calweton Equine
SPRING 2015 ISSUE
EQUINE MATTERS
20
The exact cause of keratoma formation is
unknown, but some veterinary surgeons believe
that trauma to the hoof or chronic irritation of
the sensitive laminae is linked to their
development. Injury or inflammation of the
coronary band has also been suggested as
a possible cause. Two types of keratoma are
recognised; these are spherical and cylindrical
referring to their shape.
Initial presentation is most often foot
abscessation; recurrence of the abscess at
the same site is suspicious. Diagnosis of a
keratoma is made by x-ray examination of the
foot. In some complicated cases, magnetic
resonance imaging may be necessary for
diagnosis. The resulting pressure from the
keratoma on the pedal bone typically results in
the appearance of an indentation in the pedal
bone due to loss of calcium in the bone. Once
the diagnosis has been made, treatment for
keratoma is via surgical removal. This can be
done under standing sedation and local
anaesthesia or general anaesthesia.
Surgical removal is performed by either
complete or partial wall resection and this
depends on the position, size and extent of the
keratoma. The procedure involves the use of
an electrical burr to make an incision through
the hoof wall to gain access to the keratoma
for removal. In those patients undergoing the
procedure standing this is performed sedated
with nerve blocks to remove sensation and a
tourniquet to reduce bleeding. Once the hoof
wall has been removed overlying the
keratoma, the tumour can be carefully
removed. Stabilisation of the hoof capsule is
important as the wall will become unstable if
sufficient amounts have been removed; often
a bar shoe, thermoplastic pad and crack plate
are placed by a farrier to achieve this.
Post-operative care is a prolonged process
on-going over several months as the deficit in
the hoof wall initially needs to granulate but
long term needs to grow out. In the immediate
post-operative period, dressings are changed
regularly to control bleeding and to prevent
development of infection. Administration of
anti-inflammatories is important to control
discomfort and in some cases the
administration of antibiotics may be
necessary to control infection.
Assuming minimal post-operative complications
and proper healing, the deficit in the hoof
wall can be filled with a glue or resin such as
a methacrylate or polyurethane. This cannot
be performed until sufficient healing has
occurred as when setting they produce marked
amounts of heat which can cause problems
when placed on sensitive parts of the foot.
In most cases, at six weeks onwards
post-operatively these can be applied.
Methods of preventing keratoma formation
are currently unknown mainly because
they aren't fully understood. If your horse
sustains an injury to their coronary band
this should be investigated immediately and
treated promptly.
Veterinary Surgeon
Lee Pritchard
XLEquine Practice
Calweton Equine
Spherical keratoma at the toe
One week post op
Filled hoof wall defect at six weeks
Spherical keratoma after removal
