Page 108 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.3 The foot 83

VetBooks.ir 1.141 1.142 1.143

Figs. 1.141–1.143 Hoof wall avulsion. (1.141) Hoof wall avulsion that is still attached dorsally. (1.142)
Resection of the distal portion of the avulsed hoof wall and apposition of the proximal margin of the avulsed
wall with a wire suture. (1.143) Stabilisation of the hoof wall with a rim cast.

a cast or therapeutic shoe maintains the alignment were lost, the new wall may be surprisingly cos-
of the foot with the pastern. Partial hoof wall avul- metic, and functional with therapeutic shoeing. If
sions, in which the coronary tissues are all present the avulsion involves injury to the deeper structures
and viable, are best managed by resecting the wall of the foot such as the DIP joint or navicular bursa,
1–2 cm distal to the coronary band and reconstruct- the prognosis is poorer.
ing the band (Fig. 1.142). The two sides of a coro-
nary band injury can be opposed by drilling holes in KERATOMA
the hoof wall and suturing with wire. Alternatively,
the coronary band can be reconstructed with regular Definition/overview
suture material if the outer layers of the hoof capsule Keratomas are epithelial tumours of the hoof.
have been removed first. A cast may then be applied
over the reconstruction for additional stability Aetiology/pathophysiology
(Fig. 1.143). If the alignment of the coronary band The aetiology is unknown, but prior trauma to the
is correct, a new hoof wall may grow that is grossly hoof has been associated with keratomas in some
indistinguishable from the rest of the wall, although horses. The tumours originate from the germi-
defects may persist at and below the margins of the nal layers of the epithelium of the hoof and occur
avulsion where the original coronary defect was in the wall or the sole. The tumour develops into
closed. Partial avulsions that are deemed unviable an expansile mass, usually deep to the hoof cap-
are converted to complete avulsions. Following sule (Fig. 1.144). It may cause pressure lysis of the
either complete or partial healing of an avulsion, underlying distal phalanx and/or distortion of the
therapeutic shoeing may be necessary to support the overlying hoof capsule. Histologically, the tumour
side of the foot with the injury, depending on the is characterised by rings of squamous epithelial
structural integrity of the new wall. Affected joints cells containing abundant keratin. Frequently, the
and tendons are treated accordingly. tumours are associated with recurrent secondary
infection.
Prognosis
The prognosis depends on the degree of injury to the Clinical presentation
coronary band and underlying structures. If the cor- The most common presenting symptom is lame-
onary band was intact or was successfully repaired, ness accompanied by distortion of the hoof capsule
the new wall may closely resemble the original and and recurrent infection. The infection may take the
function normally. If parts of the coronary tissues form of recurrent foot abscesses.