328 PRINCIPLES OF VETERINARY SURGERY 



Cold has a very perceptible action on the brain. Does it 

 act abruptly?' It stimulates cerebral anaemia. Is its action 

 gradual and progressive ? It ends in cerebral congestion, 

 which is absolutely opposed to the former. These different 

 manifestations may be combined in different ways and give 

 rise to a complex and variable symptomology. 



Locally cold causes different lesions, according to 

 whether the part is frozen or threatened with freezing. It 

 provokes a vaso-motor constriction, — a real anaemia, which 

 deprives the tissues of their nutritive elements and causes 

 gangrene if the action has sufficient duration. Generally 

 matters do ,not reach this point, for cold, unlike heat, has a 

 slow progressive action, and has not the same disorganizing 

 effect. It predisposes to, rather than causes gangrene. 



SYMPTOMS. — As in the case of heat, degrees of cold 

 have been designated in human surgeiy, but it does not 

 seem necessary to apply them to veterinary surgery. Freez- 

 ing caused by snow, exhibits itself in the horse, by gan- 

 grene of the skin on the fetlock and pastern, and sometimes 

 on the velvety tissue of the foot that is insufficiently pro- 

 tected ; and exceedingly tenacious ulcerations often appear 

 on the flexion surface of the pastern. Real incrustations 

 may be produced and the skin may be eliminated in shreds. 

 Stottmeister refers to the loss of the skin of the four ex- 

 tremities of a cow, and Kekeler to an analogous injury in a 

 colt. 



PATHOLOGICAL ANATOMY— Slight and transient 

 cold leads to rubification of the skin, and more severe cold 

 to blisters and gangrene, but these lesions are not immedi- 

 ately produced ; they are secondary, since the primary 

 phenomenon is a marked vaso-constriction — a stage of anae- 

 mia. If the refrigerating action yields before there has been 

 any vascular impairment resolution will be quite prompt, 

 but when the latter occurs morbid processes are positive. 



