OPERATION FOR SITFASf 459 



through about one-half inch outward from the chain. Usually 

 this causes the inner edge of the skin to slip through the 

 chain-loop, which thus spontaneously transfers the chain into 

 the incision. The chain is again drawn tight and after wait- 

 ing a few minutes for the tissues to yield to the pressure, the 

 growth is at once cut completely off with the scalpel. 



If the skin should refuse to slip through the loop when 

 incised, the chain is loosened slightly and transferred into 

 the incision, after which the operation proceeds as before 

 mentioned. 



Although the wound produced by this peculiar operation 

 is a large one, often'stretching over an area that is alarming, 

 it heals with remarkable rapidity and always leaves a much 

 smoother shoulder than ablation by dissection and suturing, 

 and the resulting scar, while hairless, is less susceptible to 

 collar injuries. 



Operation for Sitfast. 



Sitfast, a name consecrated by usage, refers to local, 

 cutaneous dry gangrene, resulting from harness pressure. 

 The constant pressure of a part of the harness or collar upon 

 a circumscribed spot destroys first the epiderm and papillary 

 layer of the skin and the slowness of the destructive process 

 leaves ample time for the moisture to evaporate therefrom. 

 If the pressure continues the process finally extends through 

 the skin, a groove of demarcation forms around the circum- 

 ference, infection enters the subjacent space, the mass falls 

 out in a single, leather-like body, and then cicatrization pro- 

 ceeds. The evolution of this process is often very slow; a 

 sitfast may sojourn without adjacent reaction for months, 

 and as it is accomplished with considerable pain and tends 

 to spread over a large area, excision (the only successful 

 treatment) should be immediately effected. 



TECHNIQUE.— After shaving the surrounding skin and 

 disinfecting the field the edge of the sitfast is lifted up at one 

 part by dissection in order to determine the depth of the 

 dead elements. When this has been determined the dissection 

 is carried around the entire circumference at the same depths 

 and then evenly underneath. If upon lifting the part off 

 ischemic zones are found to exist here and there, the excava- 

 tion is made as deep as is necessary to bring a uniform 

 capillary oozing over the whole surface. It is rarely ever 

 necessary, except in old, advanced cases, to carry the dis- 

 section entirely through the skin. 



