484 SHOULDER ABSCESS. 



do not enter the pleural sac. Sometimes both the dry and moist 

 methods are associated or alternated by allowing disinfecting fluids 

 to pass through the dressing and wound, from whence they are 

 suitably drained. Such irrigation, or frequent moistening with 

 antiseptic solutions, is useful. Dressings must be changed as soon 

 as soaked with discharge, or where high fever has set in. When 

 healthy lung protrudes through the wound it should be reduced ; 

 but when the lung is livid, or plainly infected, the protruding portion 

 should be ligatured and excised, and the chest wound carefully closed 

 and protected. Little can be done in combating pneumothorax ; 

 and in hemothorax the blood, being already clotted, is difficult to 

 remove. In septic pleuritis in horses and carnivora the thorax is 

 sometimes washed out with 1 part of corrosive sublimate to 3,000 

 of water ; for ruminants, a solution of 1 in 700 of boric acid, or a 

 lotion of alum. acet. of similar strength may be used. But such 

 treatment is seldom effectual. Weisner, experimenting on two 

 horses with 1 per cent, solution of salicylic acid, was not successful. 



V.— SHOULDER ABSCESS. 



Two varieties of shoulder abscess have been described, one super- 

 ficial, presenting similar features to subcutaneous abscesses else- 

 where ; the other of a special type, almost peculiar to harness horses, 

 always more or less deep-seated, and generally due to botryomycotic 

 infection. 



Symptoms and progress. A diffused, hard, slightly painful 

 swelling, as large as a child's head or larger, lying either in or below 

 the mastoido-humeralis muscle (levator humeri) suddenly appears. 

 The skin is sound and movable, marked lameness is seldom present, 

 though sometimes stiffness or slight lameness occurs when the abscess 

 is nearly mature. 



For some time no marked changes occur in the swelling, except 

 possibly an increase of circumference, and it may remain stationary 

 for many weeks, during which steady work may be done. Usually 

 after a few weeks, fluctuation appears at the most prominent part, 

 and on incision thick pus is discharged. The earlier the swelling is 

 punctured the more quickly it subsides. If operation is long delayed 

 the walls increase in thickness, and considerable inflammatory fibrous 

 growth remains. 



Opinions differ as to the origin of these tumours ; Franck believed 

 that they are associated with injury of the prescapular glands. 

 Hertwig, who is supported by Esser, considered that they are caused 



