Page 111 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

86 CHAPTER 1

VetBooks.ir is generally considered as a change in the shape of the most likely cause of imbalance in shod horses.
Imbalance also occurs in barefooted horses with
the hoof that is either indicative of other change that
is deleterious to function or potentially deleterious
Imbalance causes lameness by distortion of the
to function itself. As such, imbalance can be thought inadequate care or poor conformation.
of as a disruption of the normal homeostatic mech- hoof capsule and injury to other structures in the
anisms that determine the shape of the hoof. Such limb due to stress redistribution. Dorsopalmar
disruption could be caused by any event that causes imbalance is divided into broken back and broken
the distribution of force on the ground surface of the forward foot–pastern axis (Fig. 1.147). The former
foot to change. is reported to be associated with navicular disease,
Both conformation and balance refer at least in distal DDFT strain, heel bruising, haemorrhage in
part to the shape of the foot, yet it is convenient to the dorsal white line and pedal osteitis of the pal-
divide them into two concepts because of the factors mar processes. The latter is associated with dorsal
that influence them. Both are dependent on genetics sole haemorrhages and pedal osteitis. Mediolateral
and development, but balance is also affected by hoof imbalance (Fig. 1.148) is reported to be associated
growth, wear on the foot, trimming and shoeing, with sheared heels, quarter or heel cracks, sidebone,
and the nature of the horse’s work. Conformation is fracture of the palmar processes and asymmetrical
largely determined by the time a horse is skeletally bruising and pedal osteitis, although for the most
mature, whereas the balance of a foot may continu- part epidemiological evidence to support these
ally change throughout the horse’s life. Therefore, in observations is lacking.
an adult, attempting to change the limb conforma- The different changes within the foot that are
tion by altering the distribution of stresses within the described as imbalance are often interrelated, but
hoof is likely to be injurious rather than beneficial. some of them are frequently discussed as separate
Poor foot trimming and shoe placement/selection is entities.

1.147 1.148

Fig. 1.147 A broken-forward foot pastern axis with Fig. 1.148 Hoof imbalance. Mediolateral foot
lines drawn on the photograph to accentuate the imbalance with asymmetry of the heel bulbs and
broken axis. walls of the hoof, sheared and contracted heels, and
uneven bearing surface of the wall. (Photo courtesy
Graham Munroe)