Page 165 - Adams and Stashak's Lameness in Horses, 7th Edition

Examination for Lameness 131

Knowledge of and ability to detect the different types of reference to the “hip” (coxofemoral joint) in this obser­
pelvic asymmetry may be helpful to veterinary practi­ vation method is actually a misnomer as the hip joint is
VetBooks.ir accomplished by complex muscular activity in the proxi­ tor is actually observing vertical movement of the tubera
not visible under the gluteal muscle masses. The evalua­
tioners isolating lameness within the affected limb.
Decreased pelvic fall during hindlimb lameness is
coxae.
mal hindlimb, by shifting weight to the contralateral fore­ When a horse is trotting, the vertical movement tra­
limb, and by “hip hiking” as the horse attempts to use the jectory of each tuber coxae is normally asymmetric in
lame‐side hemipelvis in a similar (but not so successful) time (i.e. it is not similar to a perfect sine wave). It moves
manner as it uses its head in forelimb lameness, elevating downward during the first half of stance to reach a local
the lame‐side hemipelvis immediately before weight‐bear­ minimum at midstance and then upward as the horse
ing. Alternatively, decrease pelvic rise during pushoff‐type straightens and pushes off the hindlimb. The tuber coxae
hindlimb lameness is primarily caused by reduced exten­ then moves down a greater amount as the limb flexes
sor muscle activity, resulting in decreased propulsion of and swings forward, reaching its lowest position from
the body mass upward and forward. Because the pelvis the ground after that hindlimb pushoff. Finally, during
rises to a lower height relative to the ground after defi­ hindlimb protraction, the tuber coxae moves upward,
cient pushoff, swinging the limb forward subsequently back to its original height, in preparation for hindlimb
requires more limb flexion to prevent toe dragging. This hoof contact and the beginning of the next stride’s stance
increase limb flexion during swing creates the “hip dip” (Figure 2.122).
that occurs after stance of the lame‐side hindlimb. The pelvis is minimally rotated, and the right and left
Insufficient limb flexion and “hip dip” result in toe drag­ tuber coxae are at equivalent heights when the normal
ging, an additional sign of a hindlimb lameness character­ (i.e. not lame) horse is not weight bearing with one
ized by decreased pushoff. Because the causes of decreased hindlimb in retraction just after pushoff and one in pro­
hindlimb impact and decreased hindlimb pushoff are dif­ traction, just before impact. The pelvis is maximally
ferent, impact‐ and pushoff‐type hindlimb lameness rotated when one hindlimb is weight bearing and the
should be considered separate entities, and total amount other is swinging forward, with the tuber coxae on
of hindlimb lameness is the sum of both. the weight‐bearing side higher than the tuber coxae
on the non‐weight‐bearing side. The pelvis is rotated
toward the hindlimb swinging forward.
EVALUATION OF PELVIC ROTATION With most hindlimb lameness, total vertical move­
FOR HINDLIMB LAMENESS (THE PELVIC ment of the tuber coxae is greatest on the lame or more
ROTATION METHOD [PRM]) lame side. This may be because of both a “hip dip” (a
low position of the tuber coxae) right after pushoff of
Some veterinarians observe for hindlimb lameness at the lame hindlimb and a “hip hike” (a high position of
the trot by assessing amount of “hip hike” and “hip the tuber coxae) right before impact of the lame limb.
dip,” which are manifestations of asymmetric pelvic A “hip dip” occurs because the lame hindlimb, after
rotation in the frontal plane, instead of observing whole weak pushoff and small amplitude of pelvic rise, must
pelvis rise and fall as described above. 35,39,40 However, have increased flexion (and dipping of the tuber coxae

B D

A C
Figure 2.122. Vertical trajectories of right (solid line) and left tuber coxae at same vertical heights from the ground and the pelvis,
(dashed line) tuber coxae in horse without hindlimb lameness. (A) once again, are not rotated relative to the ground. (D) During right
Just before impact of left hindlimb and after pushoff of right hindlimb, hindlimb stance, right tuber coxae at local minimum, which is higher
both tuber coxae at same vertical heights from the ground and the than left tuber coxae local minimum when left hindlimb at midswing.
pelvis are not rotated relative to the ground. (B) During left hindlimb The pelvis is rotated to the left with the left hindlimb flexed. Source:
stance, left tuber coxae at local minimum that is higher than right Screenshots of horse animations taken (with permission) from
tuber coxae local minimum when right hindlimb at midswing. The LamenessTrainer.com (authors/developers S.D. Starke, G.C. Miles,
pelvis is rotated to the right with the right hindlimb flexed. (C) Just and S.A. May, funded by the Eranda Foundation, developed at the
before impact of right hindlimb and after pushoff of left hindlimb, both Royal Veterinary College, Hatfield AL9 7TA, UK).