364 DISEASES OF THE HORSE. 
sudden and alarming series of symptoms which have suggested the 
phrase of “ stifle out ” as a descriptive term. 
Symptoms.—The animal so affected 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 treat- 
ment 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 ord:nary 
causes, but which have remained at rest in their stables. Sometimes 
these cases are assignable to falls in a slippery stall, or perhaps slip- 
ping when endeavoring to rise; sometimes to weakness in convalesc- 
ing 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 spas- 
modic jerk, and the animal may walk or trot away without suspicion 
of lameness. Though this may end the trouble for the time, and 
the restoration seem to be perfect and permanent, a repetition of the 
entire transaction may subsequently take place, and perhaps from 
