526 



DISEASES OF THE SKIN. 



sporadic, it must be considered as a specific disease. If we describe 

 it here, it is because, from a practical standpoint, it is preferable ta 

 separate it entirely from these two morbid conditions, the infectious 

 and epizootic. 



Symptoms. Urticaria is marked by a sudden appearance of 

 blotches on the skin, which disappear rapidly. It is accompanied 

 by gastric troubles and a more or less intense fever. 



In animals which have until then been very healthy it suddenly 

 appears, and most frequently during the night, on the upper regions 

 of the trunk, the chest, croup, abdomen, and the upper part of the 

 limbs : flattened pustules of a more or less dark red color, of the 

 size of 1 to 3 centimetres, of 1 to 2 millimetres in thickness, and 

 very sensitive to the touch. By their confluence they form blotches 

 of the size of a saucer ; they are swollen (bolster-shaped) on their 

 periphery, and present a variable coloration according to the period 

 at which they are observed and the degree of intensity of the dis- 

 ease ; when of recent origin they are of a red tint, while at their 

 period of complete formation they are whitish and surrounded by 

 a violet zone. These are the only symptoms found in cases of 

 benign course. In forms of some gravity the blotches are hemor- 

 rhagic, their color varies from light red to dark red (at the place 

 of the serous transudate there are subcutaneous ecchymotic centres); 

 they are sometimes covered with scabs, which are eliminated within 

 a variable time ; in detaching these latter the hemorrhagic blotches 

 appear of rhomboidal shape. 



Gastric troubles are marked by a diminution of appetite, con- 

 stipation, and vomiting. The animals, depressed and weak, fall 

 into their litter ; the mucous membranes are much injected, the 

 breathing accelerated, the temperature often rises to 40°. In some 

 instances the gait is stiff, a phenomenon which may lead us to sus- 

 pect a rheumatismal affection of the legs. 



The course of urticaria is ordinarily rapid and its prognosis 

 benign. In less serious cases recovery is produced after one or 

 two days ; in others within four to six days. We have never seen 

 a fatal termination. The improvement is announced by expulsion 

 of softened excrementitious matters; exanthema soon rétrocèdes, 

 the blotches turn pale, become flaccid, and disappear little by 

 little. 



Differential diagnosis. Urticaria was formerly considered as 

 a "benign form of rougeV^ (hog cholera). This erroneous opinion 



