SHOULDER LAMENESS FROM RHEUMATISM. 785 



in young horses from severe exertion, and can only be detected by 

 careful palpation. On drawing the foot backwards, the animals 

 show pain. 



These conditions are usually accompanied by lameness while 

 the limb is being advanced, though none is shown when weight is 

 placed on it. After some time muscular atrophy sets in, and is most 

 marked in the region of the diseased muscles. 



Rheumatic disease of the shoulder muscles, which is especially 

 common in the levator humeri, produces similar symptoms. Pain 

 generally diminishes during movement, and may entirely disappear 

 when the animal begins to sweat. Rheumatic disease is indicated 

 by remittent or intermittent lameness, and by unusual pain after 

 slight sudden movement of the muscles, such as that produced by 

 nipping the parts with the finger, whilst powerful pressure is less 

 painful. Sometimes extensive contraction can be induced in single 

 muscles, e.g., in the levator humeri, by a light blow with the finger. 

 In disease of this character in the levator humeri, the animal's neck 

 is drawn downwards and towards the diseased side (torticollis), and 

 the muscle appears very tense and prominent. 



Piitz saw a peculiar shoulder lameness : movement was difficult, though 

 the animal showed no pain on examination. The muscles were swollen but 

 relaxed, the body sank between the limbs, and the shoulder-joint was 

 pressed away from the thorax. Post-mortem examination discovered a 

 myositis chronica fibrosa, produced by the presence of parasites. 



Blenkinsop, in Australian horses, repeatedly observed atrophy of the 

 pectoralis anticus. A deep depression was present in the pectoral region, 

 especially noticeable when the limb was drawn backwards. The diseased 

 leg was advanced when moving, without, however, being extended. The 

 shoulder-joint was turned outwards, the elbow inwards ; below this point 

 the limb was abducted, and trailed during forward movements. 



Rupture of shoulder muscles has often been seen in horses. 

 Di Nasso had a case of rupture of the serratus anticus major, 

 subscapularis and pectoral muscles from collision with a tree. On 

 placing weight on the limb the shoulder-joint was rotated outwards — 

 a sign of paralysis of the suprascapular nerve. A similar case 

 has already been described under the heading " Paralysis of the 

 Suprascapular Nerve." In horses shoulder lameness may also be 

 produced by over-extension and partial rupture of the superficial 

 pectoral muscles, due to falling or slipping. 



Rigot several times noted rupture of the subscapularis muscle in horses, 

 in consequence of the limb slipping outwards. As a rule, the tear occurred 

 near the lower insertion, and was followed by formation of exostoses on 

 the humerus. The following case was due to rupture of the triceps. A 

 riding- horse suddenly fell lame on the off fore- leg when turning sharply. 



