Page 102 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.3 The foot 77

VetBooks.ir Horses with white line disease do not have the char- 1.128
acteristic history of horses with chronic laminitis,
and those that are severely lame have a more chronic
history than cases with abscessation. The defect in
the wall is more superficial than that seen in hooves
with laminitis or abscesses, and while it has not
been specifically examined, it is highly unlikely that
there is stretching of the lamellae as seen in chronic
laminitis.

Management
The most important aspect of treatment is removal
of all undermined hoof wall, which exposes the
underlying surface to air to dry (Fig. 1.128). The
affected hoof wall does not provide effective support
to the distal phalanx and can for the most part be
removed without harm; debridement of large defects
may cause the wall on either side of the defect to
spread, requiring some form of stabilisation. If any
affected wall is not debrided, the disease will con-
tinue to spread. Several topical medications have Fig. 1.128 White line disease hoof post resection of
been used, but it has not been determined whether all overlying hoof wall.
they provide additional benefit to the debridement.
The horse is left barefoot and the lesion exposed to
air during treatment if possible. If it is difficult to should be expected in those horses without displace-
keep the surface clean, bandages may be applied, ment of the distal phalanx, and even in those horses
either dry or with a topical astringent such as 2% with displacement the prognosis for return to work is
tincture of iodine or antiseptic such as povidone– much better than for laminitic horses with rotation.
iodine. The latter is used if the debridement has been
sufficiently aggressive that the germinal epithelium HOOF CRACKS
is near the surface of the defect. If it is essential that
a horse returns to competition before the defect in Definition/overview
the wall has grown out, and the surface has been free Hoof cracks are horizontal or vertical fissures within
from evidence of disease for 2 weeks, then the defect the hoof capsule.
can be patched with a synthetic composite. Any
affected tissue still present under the reconstructed Aetiology/pathophysiology
wall will spread, causing separation of the patch Vertical hoof cracks are common. They are most
from the wall. Metronidazole incorporated into the commonly caused by poor mediolateral and/or dor-
synthetic polymer may reduce recurrence of the dis- sopalmar hoof balance. The majority of quarter
ease, but this is no substitute for adequate debride- cracks occur in feet with sheared heels/quarters. It
ment. Those horses with lameness associated with has been postulated that the displacement of the cor-
displacement of the distal phalanx should be shod in onary band associated with a sheared heel/ quarter
the same manner as a laminitic horse. causes the ungual cartilage to impinge on the axial
surface of the coronary band, which then contrib-
Prognosis utes to the development of the crack. Additional
Complete elimination of the disease may require per- causes include trauma to the coronary band, poor
sistence, but should be successful. Return to full work quality hoof horn and inadequate/infrequent hoof