PART VII. 

 DISEASES OF THE ORGANS OF LOCOMOTION. 



MUSCULAR RHEUMATISM. 



Definition. — Muscular rheumatism is a form of myositis. 



Occurrence. — Muscular rheumatism is not common in ani- 

 mals. In large animals it is most frequent in horses and 

 cattle. 



Etiology. — The causes of muscular rheumatism are un- 

 known. Cold and dampness combined are important but 

 probably only predisposing factors. In all probability the 

 immediate cause is either an infection or an intoxication, 

 although the absence of fever and localization in individual 

 muscles rather speaks against this theory. 



Necropsy. — On necropsy the muscles attacked are hyper- 

 emia hemorrhagic, and show serous exudate and cellular 

 infiltration. In some cases there is cloudy swelling and fatty 

 degeneration of the muscle fibers. In chronic cases a prolif- 

 eration of connective tissue occurs in the muscles attacked. 



Symptoms. — Characteristic of rheumatism is a suddenly 

 appearing painful condition of certain muscles which usually 

 follows exposure to cold. There is a tendency for the pain 

 to shift from one muscular group to another. The inflamma- 

 tion disappears often as suddenly and mysteriously as it 

 came but there is always a tendency to relapses. On palpa 7 

 tion the affected muscles feel tense and are very sensitive. 

 Depending upon the location of the inflammation different 

 forms of rheumatism are distinguished clinically: 



(a) Shoulder rheumatism (omalgia) which affects the 

 biceps, brachiocephalic and the supra- and infraspinati 

 muscles causing in horses shoulder lameness of the swinging- 

 leg type. 

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