364 DISEASES OF THE HOESE. 



sudden and alarming series of symptoms which have suggested the 

 phrase of " stifle out " as a descriptive term. 



Sympto'nis. — The animal so aifected 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, w^hich 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 ordinary 

 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 alwa^^s 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 awa^^ 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 i:)erhaps from 



