DISLOCATION OF THE PATELLA. 317 



as a result of accident, at any age. Young horses that suffer, off 

 and on, from this dislocation, often lose their liability to it with 

 increasing strength and age. 



The dislocation may be complete or partial. In the former 

 instance, the patella is entirely removed from ' the pulley-like 

 portion of the femur, the two prominences of which can, then, 

 be felt with the hand under the skin. In the latter and much 

 more common case, it rests on the edge of the pulley, only one 

 prominence of which will be micovered. In both, the unusual 

 position assumed by the patella will be manifest. When the 

 dislocation is complete, the affected limb is kept pointed to the 

 rear, straight and stilY; while the front of the wall of the hoof, 

 or, even, the front of the pastern, rests on the ground. The limb 

 is carried in the same manner, if the animal is made to walk, 

 which he naturally does with great difficulty. When the dis- 

 placement is partial, the lameness is similar to that just described, 

 although less in degree; and, if the horse is made to walk, the 

 patella may slip into and out of its position with a certain amount 

 of noise. Sometimes, both legs are affected. Id which case, the 

 displacement is usually partial. 



When the dislocation is partial, it may become spontaneously 

 reduced, if the animal be startled by the crack of a whip for 

 instance, and made to move forward a few paces ; or the patella 

 may be pushed into its place with the hand, while the animal 

 tries to advance the limb. When such simple measures do not 

 suffice, or when the dislocation is complete, a rope should be 

 attached to the pastern of the injured limb, passed through a 

 collar (formed of rope, for instance) round the animal's neck, and 

 should be drawn forcibly forward. The operator should then use 

 every effort to push the patella into its place ; while, to assist 

 him, the animal may be backed so as to force it to put weight on 

 the affected leg. If these methods fail, the horse should be placed 

 under the influence of chloroform, which will cause general re- 

 laxation of the muscles. No time should be lost in reducing the 

 dislocation; for if this be not done, injiu-ious changes will quickly 

 take place in the smooth surfaces of the joint in question. When 

 the patella has been replaced into its proper position, the limb 

 should be kept advanced by means of a side line fixed to its 

 pastern and passed round the neck as a collar. A long-toed shoe 

 (Fig, 104) will aid in keeping the stifle joint bent. The part may 

 be kept at rest and repair hastened by the application of one or 

 two smart cantharides blisters. As this accident is apt to recur, 

 and as the involved joint becomes more and more liable to it, by 

 repetition; we should not neglect the remedial means I have 

 described. After the effects of the second blister have gone 



