500 



DISEASES OF THE SKIN. 



time. In some rare cases, but especially when animals rub or 

 scratch themselver constantly, the process becomes aggravated ; a 

 phlegmonous inflammation is produced, which is followed by 

 ulcerative destruction of the derma, with abundant suppuration, 

 extensive depilation, and callous thickening. Similar circumscribed 

 purulent dermatitis accompanies vesiculous or pustulous eruptions 

 which are due to mechanical, chemical or violent thermic irrita- 

 tions. 



The different varieties of eczema may pass into a chronic state. 

 In benign papulous or vesiculous forms recurring cases are not 

 rare. Pustulous eczema is remarkable by its tendency to the 

 chronic condition. The persistence of the affection seems to have 

 as a principal cause the rubbing and scratching of the diseased 

 animals. 



The manifestations of chronic eczema are permanent hyperemia 

 of the skin, local hyperthermia and hypertrophy, which may treble 

 or quadruple the normal thickness. The surface of these hyper- 

 trophies is shiny ; it is the seat of a very active epidermic prolifer- 

 ation and of an abundant desquamation [squamous eczema). Little 

 by little the skin becomes dry, hard, rigid ; it is wrinkled, and 

 folds artificially made in it persist for a certain time ; the hairs, 

 which are very sparse, are erect, standing in all directions ; they 

 are often dried, brittle, or entangled like sheep's wool (compression 

 and atrophy of the hair-bulbs and of their bloodvessels by con- 

 nective tissue neoformation and retraction of the tissue) ; the diseased 

 surfaces may be completely denuded. Sometimes the skin presents 

 a granulous aspect, due to thickening, hypertrophy of the papillae, 

 which are more or less prominent. Alterations produced by serious 

 eczemas predispose to a recurrence of the trouble; an acute out- 

 break happens in the spring, when the cutaneous functions are 

 especially active. 



The general health of animals affected by eczema is ordinarily 

 but little modified. We observe only permanent agitation, rest- 

 lessness, and intense thirst. When the disease is prolonged and 

 acute outbreaks occur, continual itching, loss of heat and of 

 nutritive fluids, with reflex excitement, produce gradual emaciation 

 and cachexia. Very young or weak animals may succumb. 



The duration of acute eczema varies from one to three weeks. 

 Chronic eczema persists often for many months, even for years, 

 showing remissions of variable duration. 



