Page 119 - Adams and Stashak's Lameness in Horses, 7th Edition

Examination for Lameness 85

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Figure 2.25. Example of a long sloping pastern that is often
associated with a broken‐back hoof‐pastern axis. A long toe and a
low heel often contribute to this conformation. The weight‐bearing
surface of the foot is well forward of the metacarpus/metatarsus.

predispose a horse to injury of the navicular region,
flexor tendons, sesamoid bones, and suspensory liga­
ment (Figure 2.25). Long pasterns were also found to Figure 2.26. Normal hindlimb conformation as viewed from the
36
increase the odds of Thoroughbred racehorses fractur­ side. A line dropped from the point of the buttock (tuber ischii)
ing a front limb, and the risk of SDF tendon injury should follow the cannon bone.
2
increased with an increase in fetlock joint angle in a
study of National Hunt racehorses. 41 The relationship of the length of the bones, the angles
of the joints, and the overall height of the hindlimb often
dictate the type of action and amount of power pro­
The Hindlimbs
duced. The length and slope to the pelvis (croup) are
The hindlimbs constitute the “engine” of the horse measured from the point of the hip to the point of the
regardless of its intended use. Endurance horses typically buttock. A flat, level croup is associated with hindlimb
have longer, flatter muscles, stock horses have shorter, action that occurs behind the hindquarters rather than
thicker muscles, and all‐around horses have moderate underneath it. A “goose rump” is a very steep croup that
muscling. Lack of hindlimb musculature or a disparity places the hindlimbs so far under the horse’s belly that
between the forelimb vs. hindlimb muscle mass may sug­ structural problems may occur due to the overangula­
gest chronic hindlimb lameness problems. tion. Somewhere between these two extremes is ideal. In
general, a more flexed hip causes a more protracted
position of the hindlimb at the stance phase and a more
lateral View
horizontal femur during the swing phase. The coxal
When viewed from the side, the hindlimbs should angle (angle between the ilium and ischium) was recently
exhibit a composite of moderate angles so that shock shown to have a positive effect on performance in
absorption will be efficient (Figure 2.26). A line from the National Hunt racehorses, and the risk of pelvic frac­
point of buttock to the ground should touch the hock tures decreased with an increasing coxal angle. 3,41
and end slightly behind the bulbs of the heels. A hindlimb Probably the most important individual conforma­
in front of this line is often standing under (Figure 2.27) tional detail in sport horses is the femur. A long and for­
or sickle hocked (Figure 2.28); a hindlimb behind this wardly sloping femur places the hindlimbs more under
line is often post‐legged (Figure 2.29) or camped out the horse, which allows the horse to keep its balance
(Figure 2.30). The hindquarter should be symmetric and more easily because the limb is closer to the center of
well connected to the barrel and the lower limb. The gravity. 21,22 A forwardly sloping femur has also been
gluteal muscles should tie well forward into the back, shown to have a positive effect on soundness. A long
and the hamstrings should extend down low into the femur is thought to result in a longer stride with more
Achilles tendon of the hock. reach. A short femur is associated with the short, rapid