PARALYSIS OF SUPRASCAPULAR NERVE. 773 



animal. The causes are therefore similar to those of bursitis 

 intertubercularis. The difference consists in this, that violence to 

 the unloaded limb thrusts it back, and is apt to cause this paralysis, 

 whereas violence to the limb when supporting the body causes 

 contusion of the shoulder, backward movement being then impossible. 

 This paralysis is therefore more likely . to be produced when the 

 shoulder is struck by a heavy, slow-moving body than where the 

 blow is given suddenly ; in the latter case the biceps and its bursa 

 are endangered. 



The symptoms are explained by the loss of function in the scapular 

 muscles which extend the shoulder-joint. Whilst nothing abnormal 

 can be remarked as long as the limb is rested, sudden abduction 

 occurs immediately weight is placed on it, and at the moment when 

 the foot is perpendicularly below the body. The scapula and 

 humerus are then jerked away from the wall of the thorax. This 

 movement is best seen when the horse is slowly walked in a straight 

 line. 



The disease then is distinguished by lameness when weight is 

 placed on the limb (supporting leg lameness), by abduction of the 

 limb, and by jerking of the shoulder outwards at the moment when 

 the leg is perpendicular. Atrophy of the paralysed muscles occurs 

 later, and is most marked in the supraspinatus and infraspinatus, 

 whilst the deltoid, which receives its innervation from the circumflex 

 nerve, remains intact. The atrophy is rendered more noticeable by 

 the projection of the spine of the scapula. 



Roloff saw a horse which had suddenly exhibited double- sided shoulder 

 lameness during heavy work, and found marked atrophy of the extensor 

 muscles. The shoulder- joint was thrust outwards. In this case probably 

 there was double-sided paralysis of the suprascapular nerve. In cattle, 

 on the other hand, a somewhat similar condition is caused by over- extension 

 or relaxation of the adductor group (subscapularis and teres major). It 

 is seen in particular races, such as the Holsteiners, especially in winter ; 

 in summer, when the animals are pastured, it often disappears. 



Prognosis and course. Paralysis caused by mechanical injuries 

 is known to be less favourable than the rheumatic forms, and 

 treatment is often unsuccessful. As a general rule, prognosis is much 

 less favourable than in paralysis of the radial nerve, though recovery 

 sometimes occurs in six to eight weeks. Otherwise, and especially 

 if the lameness continue severe — -that is, if the difficulty in movement 

 has not begun to disappear — -there is little hope. Of five cases seen 

 at the Berlin school, three alone recovered, though Kattner effected 

 a cure in six weeks. Of ten cases of suprascapular lameness seen 

 between 1S75 and 1890. three were discharged improved and four 



