PRINCIPLES OF VETERINARY SURGERY 69 



leaving a depression that is not always entirely refilled with 

 bone tissue. 



The separation of necrotic bone from its contiguous living 

 bone tissue occurs through the active proHferation of the 

 cells of those portions of the Haversian canals, medulla and 

 periosteum that immediately surround the diseased area. The 

 cells of these structures build a bed of new tissue between 

 the dead and the living tissues that is analogous to the gran- 

 ulations which underlie gangrenous soft structures. The 

 process of separation is hurried somewhat, in infected cases, 

 by the dissolving influence of bacterial ferments. 



SYMPTOMS. — Traumatic gangrene is always mani- 

 fested by intense pain at the seat of the injur). 

 When located in the limbs there is severe lame- 

 ness of several days' duration before the true na- 

 ture of the disturbance can be determined. The 

 skin then becomes cold, less sensitive, moist, as if per- 

 spiring, and finally sheds its hairs. If the hair surrounding 

 the diseased area is shaved the line of demarcation can be 

 seen, and the tissues within its boundary are found to emit 

 an offensive smell. After several more days the slough falls 

 off and leaves the granulating surface exposed. At this pe- 

 riod, if the gangrene has not transgressed upon the neighbor- 

 ing synovials, the lameness ceases and the wound heals 

 without further event, but leaves a hairless scar as an in- 

 delible blemish. 



Extensive gangrene progresses in much the same 

 manner, with the exception that the systemic disturbances 

 are grave and usually terminate the patient's existence be- 

 fore the gangrenous area has separated from the surrounding 

 living tissues. A whole limb, the whole withers, the entire 

 poll or the buttocks may become the seat of an extensive 

 gangrene, — sphacelus, — that rapidly terminates fatally. In 

 these ciases the pulse is fast, the temperature high, the move- 



