Page 99 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

74 CHAPTER 1

VetBooks.ir 1.123 horses would support this hypothesis. Additionally,
it is important to preserve the sole when its thickness
has been reduced following displacement of the dis-
tal phalanx. These objectives are titrated against the
severity of the disease. The effectiveness of treat-
ment is best gauged by the comfort of the horse and
whether the horse’s feet land flat. The techniques
that are currently used most widely for shoeing are
heart-bar shoes, egg-bar shoes in conjunction with
silicone putty sole support, one of two commercial
shoes (the Aluminum Four Point Rail shoe/Rocker
Fig. 1.123 A four-point rail shoe formed here by two shoe [Nanric Inc.], Fig. 1.123, and the Equine Digit
components of the Equine Digital Support System: Support System [Equine Digit Support System, Inc.])
an aluminium (or aluminum) Natural Balance Shoe or the wooden shoe (Steward Clog) (Fig. 1.124).
combined with plastic wedges called rails. The rails Pain is best controlled with phenylbutazone as
elevate the heels and because they are attached to needed, although other NSAIDs may also be used.
the axial side of the branch of the shoe, improve Rest must be balanced against the benefits of exer-
mediolateral breakover. The rails come in three cise. Occasionally, tenotomy is required to decrease
different sizes and are bolted to the shoe after it has the tension in the DDFT more effectively than can
been nailed to the foot. This allows the amount of be achieved with therapeutic shoeing. It is primar-
heel elevation to be adjusted after the shoe has been ily indicated in horses that are showing progressive
attached to the foot. rotation of the distal phalanx, horses with rotation
and thin soles that are displaying persistent pain
1.124 despite all other attempts to control it, and in horses
with secondary flexural deformities of the DIP joint.
Partial hoof-wall resections and hoof-wall grooving
are used to try to correct the concavity that occurs
in the dorsal hoof wall as the foot grows out by
mechanically dissociating the new hoof growth at
the coronary band from the stresses at the ground
surface of the wall caused by weight bearing. The
efficacy of these procedures is the subject of debate.
Abscesses should be drained, preferably through
Fig. 1.124 A wooden clog shoe. the distal wall rather than the sole. Very rarely, the
distal phalanx is debrided if septic osteitis develops,
but this should only be undertaken with great cau-
the length of the lever arm as the foot breaks over. tion because radiographs do not readily differentiate
Weight bearing by the most severely affected lamel- between osteolysis secondary to infection and oste-
lae is reduced, and this takes the form of increas- olysis secondary to pressure/damaged vasculature.
ing the ground/shoe surface contact in the palmar The latter is far more common.
aspect of the foot. How this is done and to what The treatment of horses with distal displacement
extent depends on the trim and thickness of the sole of the distal phalanx is more problematic. It is associ-
(i.e. thin soles are painful when subject to pressure). ated with loss of support of the distal phalanx by the
The heels may be elevated to decrease the tension lamellae around the circumference of the foot, and so
in the DDFT. This is thought to decrease the ten- shifting weight from one part of the foot to another
sion in the dorsal lamellae caused by the moment is unlikely to be successful. In addition, there is no
opposing the pull of the tendon, and although this rotation of the distal phalanx about the DIP joint
is debated, the clinical response observed in many that can be neutralised. Standing a horse on a soft