PRINCIPLES OF VETERINARY SURGERY 67 



ligaments, tendons and aponeuroses will remain attached to 

 the living portions indefinitely without material change in 

 color, strength or texture. They, however, separate from 

 their bony attachments and surrounding tissues, and may 

 thus be recognized from the living tendinous tissues. The 

 "line of demarcation" readily forms in the skin, in bone, in 

 muscle and in the parenchymatous organs. Slowly developing 

 gangrenes of the skin caused by moderate but constant 

 pressure often become dry and remain attached to the sub- 

 jacent tissues (sit-fast), but the line of demarcation is never 

 wanting as in the case of white, fibrous organs, such as 

 tendons. 



The line of demarcation is serrated and irregular in all 

 of its outlines. It may be deep at some points and shallow at 

 others. When the slough or sequestrum is removed it un- 

 covers typical, rosy granulations which proceed to cicatrize 

 in the usual manner. 



Gangrene is often described as moist gangrene and dry 

 gangrene. This classification is not without fault. It is apt 

 to be misleading for both of these varieties may be due to the 

 same cause, and the reputed cause of one may determine the 

 other. For example, an inflammatory condition may cause 

 dry gangrene as is observed in sit-fast and decubitus of 

 animals, while the occlusion of a large artery which is sup- 

 posed to cause only the dry form may, in reality, produce the 

 moist variety. The kind of gangrene is determined by the 

 amount of fluids the tissues contain at the time the nutrition 

 was arrested, and upon their capability of preventing its 

 evaporation, and not upon the cause. 



The gangrenous tissues may also contain gas as in the 

 case of malignant oedema and symptomatic anthrax. Gan- 

 grenous processes even of small areas always cause some 

 systemic disturbances. When the area is great grave dis- 

 orders always supervene and death may ensue from septic 



