imperfect development of the external lip of the trochlea. Such a deformity
subjects the animal to frequent luxations.

_The symptoms may vary_. The displacement may be first noticed when the
horse is backed out of the stall or turned quickly. A slight "hitch" in the
movement of the limb is noted, that is followed by more noticeable flexion
of the hock than normal. In case the luxation is more permanent, the horse
stands quietly with the affected leg held stiffly and extended backward.
When made to move forward, it hops on the well leg and carries the affected
one, or drags it on the toe. If both limbs are affected, the animal is
unable to move. The inability to move the limb is due to the patella
resting on the external lip of the pulley surface, and a locking of the
stifle- and hock-joint.

This accident is annoying, and in case the horse is subject to it should be
considered an unsoundness.

The following _treatment_ may be recommended: The luxation may be reduced
in the large majority of cases by backing or turning the animal. If this
does not reduce the displacement, a collar should be placed on the animal,
and a hobble strap fastened to the pastern of the involved limb. One end of
a long rope is tied to the collar, passed backward between the front limbs,
through a ring in the hobble and back over the outside of the shoulder and
under the collar. While an attendant pulls the limb a little forward with
the rope, the operator takes hold of the foot and attempts to flex the
limb, at the same time pushing inward on the patella. After reducing the
luxation it is advisable to tie the rope to the collar, so that the limb is
carried forward. This prevents the animal from throwing weight on the foot.
It may be advisable to tie the animal so that it can not lie down, if the
foot is to be left hobbled for a few days. A fly blister should be applied