Page 123 - Adams and Stashak's Lameness in Horses, 7th Edition

Examination for Lameness 89

point toward one another, and the feet are widely sepa­ the same as the angle of the toe. However, the angle of
4,9
rated. Cow‐hocked conformation is a common defect, and the hoof is less important than the hoof‐pastern axis
VetBooks.ir flaw. However, others feels that a slight valgus deformity relative to heel wall length should be approximately
some believe that it is a serious hindlimb conformation
when evaluating foot conformation. Toe wall length
36
2 : 1 in the forefoot and 2 : 1.5 in the hindfoot. Break‐
of the hindlimbs, provided that the metatarsal bones
4
remain vertical, is not a cause for concern. Sickle hocks over should occur squarely over the center of the toe
29
and cow hocks can occur concurrently and may have a and not over the medial or lateral portions of the toe.
compounding effect on hindlimb lameness problems. The frog should be large and well developed with a good
cleft, have normal consistency and elasticity, and be dry
and soft. It should divide the sole into two nearly equal
Base‐narrow
halves, and the apex should point to the center of the
Base‐narrow conformation of the hindlimbs means toe. In most horses, the apex of the frog should end
that the distance between the center of the feet is less than approximately 1–1 1/2 inches behind the toe. 7
the distance between the center of the limbs in the thigh
region, when viewed from behind (Figure 2.34). This is
observed most commonly in heavily muscled horses. It the hindFoot
causes excessive strain on the lateral aspect of the limb, The hindfoot is usually narrower, has a larger hoof
and most of the horse’s weight is placed on the outside of angle, and has a more pointed appearance at the toe than
the hooves. Base‐narrow conformation is often accompa­ the forefoot (Figure 2.35). Break‐over should be evi­
4,5
nied by “bowlegs” or a condition in which the hocks are dent straight over the toe, and the frog should divide the
too far apart. The limbs may appear fairly straight to the sole into equal halves. The mean hoof angle in the hind­
hock and then deviate inward, and the hocks may bow foot is usually 55° or greater, and there should be no
outward during movement. defects in the wall. 4,36 The sole of the hindfoot is normally
more concave than that of the forefoot.
Conformation of the Foot
Hoof anatomy and conformation are also discussed Medial–Lateral Hoof Balance
in Chapters 1 and 11.
ML hoof balance is often used to describe the rela­
tionship between the two halves of a hoof when viewed
the ForeFoot from the front and the levelness of the coronary band
compared to the ground surface (Figure 2.37). It is
Ideally, the forefoot should be round and wide in the
heels, and the size and shape of the heels should corre­ used to assess the symmetry (or asymmetry in many
cases) and can suggest the type of concussive forces
spond to the size and shape of the toe. The bars should
be well developed (Figure 2.35). The wall should be on the hoof wall. In general, the coronary band should
be level medial to lateral and parallel to the ground.
thickest at the toe and should thin gradually toward the
heels; the inside wall should be slightly straighter than In addition the lateral and medial aspects of the hoof
wall should be approximately the same length and
the outside wall. The sole should be slightly concave
medial to lateral and front to back, but excessive con­ angle.
cavity may suggest a chronic foot problem. There should
be minimal contact between the ground and the sole,
and toe lengths of greater than 1 1/2 inches cranial to
the apex of the frog when viewed from the bottom of
the foot may suggest excessive toe length.
The mean hoof angle of the forefoot is usually 50°–
55°, and the angle of the heel should be approximately

Bulbs
Heel
Central sulcus of frog
Angle of wall
Bars
Collateral sulcus
Quarter
White line

Apex of frog
Wall
Toe Sole

Figure 2.36. Normal hindfoot (compare with Figure 2.35). The
Figure 2.35. Normal forefoot with structures labeled. toe of the hindfoot is more pointed than that of the forefoot.