SHOULDER LAMENESS FROM RHEUMATISM. 
528 
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. 
Bigot 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. The 
lameness increased with movement, and was distinguished by the lame leg 
being so much adducted that it crossed the other leg. Seven weeks afterwards 
the animal was killed as incurable. 
A horse which four months previously had suffered from the thoracic form 
of influenza, showed cramp of the muscles of one side of the neck and of the 
fore limb of the same side, best seen in the stable when the animal moved 
the affected parts. It made sudden nodding motions with the head, lifted 
the affected fore limb, and after some seconds again set it on the ground. 
Oscillating movements, lasting for five minutes at a time, sometimes occurred 
in the muscles of the left side of the neck, particularly in the levator humeri. 
Repeated injections of veratrin were followed by recovery in three weeks. 
There is no difficulty in diagnosing such cases, but the prognosis can 
only be based on a thorough knowledge of the local anatomical changes. 
(3) Shoulder lameness may be caused by disease of the scapula or 
humerus. Though fractures are generally easy to recognise, fissures 
may elude the closest examination. Periostitis and the formation of 
exostoses are common on the scapula and humerus. 
Gerke, in making a post-mortem of a horse which had suffered for two 
years from shoulder lameness, found an exostosis on the inner side of the 
head of the humerus. The connective tissue surrounding it appeared 
thickened, and formed, along with the exostosis, an “ extraordinary articular 
surface.” The radial nerve was smaller than on the sound side. The horse 
moved the limb in circles, but could still place weight on it. The lameness 
only occurred at a trot, but did not disappear with work. Similar cases have 
repeatedly been seen. 
