448 



DISEASES OF THE SKIN 



by the animal scratching, biting or gnawing the itchy surface, particu- 

 larly when the sore is on the side where the animal can scratch it with 

 the hind legs, or on the thighs or back where he can bite it. In rare in- 

 stances the animal may so lacerate the affected portion as to cause 

 permanent loss of hair. The course of this disease depends on whether 

 it is treated early, for if neglected its course is apt to be slow or it is 

 apt to degenerate into the chronic form, particularly in older animals. 



Chronic Eczema. Dry Eczema. Scab Mange. — The second type 

 shows from the beginning an inclination to extend. In is generally 



Fig. 159. — Chronic eczema of the back. 



observed in sluggish, well nourished dogs, and while it may occur in all 

 breeds of dogs, it is more apt to be seen in short-haired dogs. It com- 

 mences on the back at the root of the tail and extends gradually up the 

 centre of the back, each succeeding attack going a little further forward 

 until it finally reaches the neck. It is sometimes observed at the base 

 of the ear, around the anus and the extremities; the scrotum is also a 

 seat of the disease, and in exceptional cases the entire body is attacked 

 (general eczema). 



In the early stages we see it as eczema erythematosum with for- 

 mation of scattered papules. These are scratched open on account of the 



