44 LAMENESS IN THE HORSE. 



weight upon it. Therefore, when walking slowly on smooth 

 ground nothing unusual can be noticed, but should the 

 animal strike its toe against anything, stumbling is 

 frequent, all joints from the elbow down are flexed and there 

 is danger of falling. Sometimes lameness is only seen after 

 exercising on heavy ground. Animals which have been 

 lame and have improved acquire a peculiar gait, together 

 with active contraction of the muscles of the shoulder, the 

 leg is slung forward, the olecranian muscles being unable to 

 exert the function fully. 



Inspection {partial j^ciralysis). — At the moment the lame 

 supporting leg is perpendicularly under the chest, there 

 is a sudden forward jerk of the scapula and humerus. 

 This involuntary movement is clearly seen as the horse 

 walks slowly past the observer. 



Differential Diagnosis. — This lameness is liable to be 

 mistaken for supra-scapular nerve paralysis, but is 

 distinguished from it by the fact that in the latter the 

 shoulder is abducted, whereas in partial paralysis of the 

 radial nerve the shoulder and humerus are jerked in a 

 forward direction. Transverse fracture of the ulna and 

 rupture of the extensors of the phalanges show similar 

 symptoms, yet palpation will settle the question. 



7.— Paralysis of the Brachial Nerve Plexus. 



History. — Sudden lameness following a severe fall, etc. 



Inspection. — In complete paralysis movement is impos- 

 sible, but when the leg is passively extended and brought 

 into a normal position it is able to support the weight of 

 the body, especially when the radial nerve is not paralyzed ; 

 while even then there is necessarily more or less difficulty - 



