ECZEMA IN THE DOG. 285 



localised on the body, neck, and ear. In one the upper surface of the 

 neck, shoulders, and back presents a large inflamed patch partially 

 denuded of hair, and almost entirely covered with a viscous, yellowish, 

 purulent material ; the skin is thickened, infiltrated, and shows trans- 

 verse folds ; the periphery of this patch is sharply circumscribed by a 

 deep red sinuous line, outside which is a narrow hyperaemic zone. In 

 another the lower surface of the neck is the seat of an eczematous 

 zone offering nearly the same characters. A third showed a few days 

 ago a discharging and very painful area on the back. The process has 

 now arrived at the period of desiccation ; the skin is covered with thin 

 crusts, is no longer so sensitive, and is hardly swollen. In a poodle 

 affected with double otitis externa, marked by abundant discharge and 

 great sensitiveness, the integument lining the external ear is still 

 swollen and red, but the discharge has greatly diminished, is no longer 

 offensive, and the itching has disappeared. Another case shows 

 auricular eczema complicated with othasmatoma (oedema of the flap of 

 the ear) ; the incessant shaking of the ears has caused separation of 

 the skin from the subjacent tissues, and the formation of a cyst 

 prominent on both surfaces of the flap of the ear. 



Histological study of the lesions of acute eczema shows that the 

 process is generally limited to the superficial layer of the dermis. The 

 rete mucosum is the seat of oedematous inflammation, and of a more 

 or less abundant immigration of lymphatic cells ; the epidermis is 

 swollen and softened by the exuded serosity, vesicles form, and the 

 epidermis becomes detached or exfoliated. The vesicles develop be- 

 tween the rete mucosum and the stratum corneum ; they contain a 

 serous liquid, leucocytes, large polynuclear epithelial cells, and micro- 

 cocci. The more intense the inflammation, the greater the amount 

 of exudate and the more abundant the infiltration of leucocytes. The 

 inflammatory changes extend to the entire thickness of the corium, in 

 which purulent centres may develop, partial destruction of tissue 

 occur, and portions of the papillary layer be lost in consequence 

 of external irritation. To sum up, acute simple eczema is an exu- 

 dative inflammation affecting the dermis and epidermis, and producing 

 lesions comparable to those of a superficial catarrh of the skin. 



