6i3 



CHAPTER X. 



DISEASES- OF THE SKIN. 



SKIN DISEASES in the dog constitute no inconsiderable proportion of all the ailments the animal 

 is subject to. 



It is only of late years, however, that much interest has been taken in this branch of 

 canine medicine. If we look into the older works on dog diseases, we shall find very imperfect 

 accounts of it indeed. More recently, Mayhew describes five different forms of skin diseases ; 

 but we cannot agree on the whole with the style of his treatment, and even he himself has frankly 

 hinted that he was in a manner working in the dark. 



It is only very lately, however, that the researches of such men as Fleming, Gruby, and Mr. 

 Hunting, aided by the microscope and experiment, have enabled us to adopt a better and more 

 useful classification, and really rational treatment. To Mr. Hunting's excellent paper on " Folli- 

 cular Mange," indeed, we are indebted for present success in the cure of a class of most troublesome 

 cases, which, in times gone by, we had often looked upon as beyond the power of medicine 

 to remedy. To a great extent, too, we also follow his plan of treatment in other forms of 

 cutaneous disease, modified or altered at times to the circumstances and constitution of the canine 

 patient. 



Before going on to describe a few of the most important cutaneous affections, let us take 

 a brief glance at the skin itself, and see what is its structure, and what are its nature and 

 functions. 



The skin, with its appended hairs, is the outside protective covering of an animal's body. 

 It is composed of two portions or layers. The outer, usually called the scarf skin, or, more 

 refinedly speaking, the cuticle or epidermis, is devoid of feeling, as it is unsupplied with nerves 

 which, along with the minute capillary blood-vessels, end in the inner or true skin. And it is 

 this inner skin that secretes the outer, in several layers of nucleated cells, those cells nearest the 

 true or sentient skin being rounded, those exposed to the air being flattened, and peeling off in 

 dust or dandruff. 



Under the epidermis lies the true skin, closely joined to the structures under it by areolar or 

 connective tissue. The outer surface of the true skin is rather peculiar. It is not smooth, but 

 is covered with minute elevations called papillae. They increase the sensation of touch, many 

 of them having very small nerves distributed through them ; other papillae have no nerves, but 

 blood-vessels instead, and as they project some distance into the epidermis they are believed by 

 physiologists to nourish it. 



Now there are one or two things, both of interest and moment, to be noted about the cutis, 

 or true skin. 



Herein are situated the sweat-glands, also the oil-glands, and the hair-follicles. In man, and 

 in many other animals, the sweat-glands are very tortuous ; in the dog they are more simple, 

 opening by a funnel-shaped aperture or pore externally in the epidermis. These are the glands 

 which secrete the perspiration. In man, and also in the horse, there are two states of perspiration, 



