DISEASES OP THE MUCOUS BURSA 243^ 



^ve a common exam,ple of purulent m,yosUis. 



The so-called shoulder abscess of the horse. 

 Eov) is this shoulder abscess formed ? 



The large, circumscribed globular swelling, at times the 

 size of a man's head, either develops in the mastoido humer- 

 alis at the point of the shoulder, or in the lymph glands right 

 helowthe muscle, but always involving it. It seems that two 

 f^iCtors are actively concerned in the production of this 

 a*bscess. Pathologically speaking, it represents a purulent 

 myositis, the pus being enclosed by a fibrous capsule of vari- 

 able thickness, which capsule again is the result of an inter- 

 stitial myositis. Contusion and subsequent infection with 

 pus-producing germs are essential etiological factors. It is 

 my experience that the vast majority of these deep and 

 chronic abscesses are found on the right side of the horse, 

 jflaich. supports the assertion that bruising is necessary for 

 jihe entrance of bacteria belonging to the streptococci and 

 staphylococci, and at times botryomyces. Most likely the- 

 contusion lowers the vitality of the tissues, the germs being 

 carried into them by the lymph channels, where they develop 

 either in the mastoido humeralis, producing a cellular infil- 

 tration and next an abscess, or the germs are deposited in the^ 

 lymph glands below the muscles, in which case there is a 

 primary chronic suppurative lymphadenitis with a secondary 

 chi;onic interstitial myositis. 



Name some diseases where multiple metastatic muscle 

 abscesses are seen. 



In the streptococcus distemper of the horse and in 

 pjemia. 

 Outline the treatment of pwrulent myositis. 



Incise the parts and secure drainage, and employ anti- 



