22 LAMENESS OP THE HORSE 



spontaneous reposition always results ; while a fixed luxation does 

 not reduce spontaneously but remains luxated until reposition 

 is effected by proper manipulation and treatment. Fixed luxa- 

 tion may be of such character as to be practically irreducible 

 because of extensive damage done to ligaments or cartilage. 

 Where a complete luxation of the metacarpophalangeal joint 

 exists, it is probal)le that in most cases sufficient injury to col- 

 lateral and capsular ligaments has been done to render com- 

 plete recovery improbable, if not impossible. 



Temporary luxation of the patella is a common affection of 

 tbe horse and fixed luxation of this bone also occurs. As a mat- 

 ter of fact, in the horse, patellar luxation is tbe one frequent 

 affection of this kind. 



As a rule, complete disarticulation immobilizes the affected 

 joint and in most instances there is noticeable an abnormal prom- 

 inence in the immediate vicinity — in patellar luxation, the whole 

 bone. In other instances the articular portion only, of the af- 

 fected bone is malpositioned. Usually, luxation and fracture 

 may be differentiated in that there is no crepitation in luxation 

 and more or less crepitation exists in fracture. 



It is evident, when one considers the symptomatology and 

 nature of the affection, that fixed luxation is usually caused by 

 undue strain or violent and abnormal movement of a part. 

 Joints having the greater freedom of movement are apt to suffer 

 luxation more frequently. 



Arthritis. 



The study of arthritis in the horse is limited to a considera- 

 tion of joint inflammations which, for the most part, are of 

 traumatic origin. Unlike the human, the horse is not subject 

 to many forms of specific arthritis — tubercular, gonorrheal, syph- 

 ilitic, etc. 



A practical manner of classification of arthritis is traumatic 

 and metastatic. 



Traumatic arthritis may result from all sorts of accidents 

 wherein joints are contused. Such cases may be considered as 

 being caused by direct injuries. Instances of this kind, depend- 

 ing on the degree of insult, manifest evidence of injury which 



