ected stands quietly and firmly in his
stall, or perhaps with one of his hind legs extended backward, and
resists every attempt to move him backward. If urged to move forward he
will either refuse or comply with a jump, with the toe of the disabled
leg dragging on the ground and brought forward by a second effort. There
is no flexion at the hock and no motion at the stifle, while the
circular motion of the hip is quite free. The leg appears to be much
longer than the other, owing to the straightened position of the thigh
bone, which forms almost a straight line with the tibia from the hip
joint down. The stifle joint is motionless, and the motions of all the
joints below it are more or less interfered with. External examination
of the muscles of the hip and thigh reveals a certain degree of
rigidity, with perhaps some soreness, and the stifle bone may be seen
projecting more or less on the outside and upper part of the joint.

This state of things may continue for some time and until treatment is
applied, or it may spontaneously and suddenly terminate, leaving
everything in its normal condition, but perhaps to return again.

_Cause._--Pseudo-dislocation of the patella is liable to occur under
many of the conditions which cause actual dislocation, and yet it may
often occur in animals which have not been exposed to the ordinary
causes, but which have remained at rest in their stables. Sometimes
these cases are assignable to falls in a slippery stall, or perhaps
slipping when endeavoring to rise; sometimes to weakness in convalescing
patients; sometimes to lack of tonicity of structure and general
debility; sometimes to relaxation of tissues from want of exercise or
use. A straight leg, sloping croup, and the young are predisposed to
this dislocation.

_Treatment._--The reduction of these displacements of the patella is not
usually attended with difficulty. A sudden jerk or spasmodic action will
often be all that is required to spring the patella into place, when the
flexion of the leg at the hock ends the trouble for the time. But this
is not always sufficient, and a true reduction may still be indicated.
To effect this the leg must be drawn well forward by a rope attached to
the lower end, and the patella, grasped with the hand, forcibly pushed
forward and inward and made to slip over the outside border of the
trochlea of the femur. The bone suddenly slips into position, the
excessive rigor of the leg ceases with a sp