Page 115 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

90 CHAPTER 1

VetBooks.ir band, not expansion at the ground surface. Lowering Attachment of the shoe
Incorrect nail placement can cause lameness. If it
the heels of an upright foot may be counterproduc-
tive if the cause of the high heels is not addressed.
underlying the hoof capsule, it will cause immedi-
Lowering the heels of a horse with palmar foot pain directly damages the sensitive tissues immediately
may cause a broken forward foot–pastern axis to ate lameness (nail prick or bind). The diagnosis can
straighten or a straight one to break back, both of be confirmed by localising the pain to a specific
which may increase pain from the navicular bone nail with hoof testers or identifying the incorrect
and bursa, or tension in the DDFT. Sheared heels placement on shoe removal. Removal of the nail
are usually treated by shortening the long heel/ should resolve the problem. The nail hole is then
quarter so that both heels are level with the base of infused with an antiseptic. More insidiously, a nail
the frog; the foot is then frequently shod with a bar that remains within the hoof capsule, but impinges
shoe to minimise movement between the heels. on the sensitive tissues (nail bind), may cause pain
secondary to pressure on the sensitive tissues or
Prognosis cause microfracture of the hoof wall internally, with
The prognosis for acute imbalance associated with subsequent introduction of infection (Fig. 1.158).
secondary pathology that is readily reversible is Lameness does not usually occur for several days
good. The prognosis for chronic imbalance, particu- following shoeing, but as with direct puncture of
larly if it is associated with degenerative conditions,
is guarded to poor.
1.158
TRIMMING AND SHOEING AS
A CAUSE OF LAMENESS

Overview
Trimming and shoeing may both cause lameness,
although the incidence is unknown. Poor trimming
may cause a foot to become unbalanced. Trimming
the medial and lateral walls unevenly creates a
mediolateral imbalance. Similarly, inappropriate
trimming of the heel and/or toe may create a broken
foot–pastern axis. Leaving the toe too long creates a
dorsopalmar imbalance or broken back foot–pastern
axis. Leaving the heel too long may create a broken
forward axis. Trimming the sole too thin causes
undue pressure on the underlying sensitive struc-
tures and predisposes them to bruising.
Attaching steel shoes with nails to horses’ feet
has some detrimental effects on the biomechanics
of the foot, including decreased expansion of the
foot, increased maximum deceleration of the foot,
increased frequency of vibrations as the foot con-
tacts the ground and an increase in the maximum
ground reaction force. Despite these effects, shoeing
is remarkably well tolerated and, indeed, frequently
considered necessary, depending on the nature of Fig. 1.158 A foot in which several of the nails
the horse’s work. Both the attachment of shoes and have been placed too close to the sensitive laminae
shoe selection can cause lameness to develop. (nail bind). (Photo courtesy Graham Munroe)