Diseases of the Skin.—External Parasites. 201 
rise to it. Filth and neglect favour parasitic development, 
but do not of themselves produce the disease. 
Symptoms.—Ordinary or sarcoptic mange is characterised, 
at its earliest period, by intense itching. If the skin of the 
affected part is examined, there will be observed small 
red points like flea-bites. These eventually become 
pustular, and break, exuding a serous fluid, which pro- 
duces thick, dark crusts, which are ultimately cast off, 
leaving the part denuded of hair, and of a bleached appear- 
ance. 
The violent scratching attendant on the affection 
throughout, creates extreme soreness, and frequently open 
wounds. The hair about the affected region becomes 
matted together, and the animal is rendered an object of 
disgust and pity. 
Aan s 
Fic. 23. 
Acarus FoLLIcULORUM. Ma- 
TURE SPECIMENS. @, MouTH ; 
6, PAPILLA ON EACH SIDE ; ¢, 
SarcopTes CANIS. (GERLACH.) FEET. (FLEMING.) 
Fic. 22. 
The disease, it not checked early, rapidly extends to the 
