RADIAL PARALYSIS IN THE HORSE. 69 



These cases may be divided into three groups, viz. Complete, Incom- 

 plete, and Partial Paralysis. 



In Complete Paralysis the joints of the affected limb, with the 

 exception of the shoulder, are usually flexed when the horse is resting. 

 In consequence of loss of power in the triceps and anterior brachial 

 muscles, the arm is extended and straightened on the shoulder, the 

 scapulo-humeral angle is open, and the elbow depressed. The forearm 

 is flexed on the arm by the contraction of the coraco-radialis, while 

 the metacarpus and plalanges are bent by the action of the posterior 

 antibrachial muscles. The knee is carried in advance, level with, or in 

 front of, a vertical line dropped from the point of the shoulder. The 

 hoof is usually rested on the toe, but when advanced beyond the above- 

 mentioned vertical line it may be placed flat on the ground, the joints 

 then being less markedly bent. When the limb as a whole is flexed, 

 it may be brought into normal position by thrusting back the knee with 

 sufficient force to counteract the action of the flexor muscles. 



In walking, the shoulder and arm are more or less "carried," the 

 lame limb being moved as a whole ; but as the lower portions of the 

 limb are insufficiently extended, the stride is much shortened. The 

 least attempt at placing weight on the leg causes all the joints to 

 become flexed, and the shoulder and arm to suddenly drop ; the animal, 

 feeling itself falling, instantly transfers weight to the other limb. At a 

 more rapid pace the animal goes on three legs, as though suffering from 

 some exceedingly painful condition. 



Incomplete Parahsis may either constitute a stage in recovery from 

 complete paralysis, or an independent condition. At rest the limb is 

 held as in the preceding form, but the entire plantar surface of the hoof 

 more frequently comes in contact with the ground. In moving, lame- 

 ness is less marked, and instead of occurring at every step may only 

 appear at intervals, varying in length with the degree of paralysis, 

 rapidity of movement, and smooth or rough character of the ground.. 

 The limb is slowly advanced, the stride shortened, and the hoof carried 

 or dragged along the ground. The animal stumbles over the smallest 

 obstacle, the limb immediately becoming flexed. 



In Partial Paralysis most of the muscles supplied by the radial 

 retain their function, and disturbance is much less marked. As a 

 rule, the position of the limb at rest is normal. During movement it 

 is freely extended, the stride is of ordinar}- length, and the joints do not 

 collapse when weight is placed on the limb. Slight lameness is visible 

 at a trot, the shoulder and arm being more or less markedl}- carried 

 forward, without, howe\'er, rolling outwards, as in paral}-sis of the supra- 

 scapular nerve. 



