332 



THE DOG IN DISEASE. 



pendent on vegetable parasites are ringworm {Tinea ton- 

 siirans) 2iX\difavus. 



Ringworm occurs in more or less circular, well-defined 

 patches, from which the hair falls, and which are covered 

 with a fine scurf. 



Favus is characterized, after the earliest scurfy stage, 

 by peculiar crusts of a sulphur-yellow color and a smell of 

 mice. Beneath these, cup-shaped ulcers are found. In 

 both diseases spores or branches {mycelium) of a vegetable 

 growth (mold) may be discovered by the microscope. 



Follicular Mange is caused by a sort of mite {Acarus 

 folliculorum\ which lodges in the hair follicles and seba- 

 ceous glands and sets up 

 infiammation. It is likely 

 that a vegetable, fungoid 

 growth akin to that caus- 

 ing ringworm is an addi- 

 tional source of the mis- 

 chief. 



Sarcoptic Mange, or 

 dog itch, is due to a mite 

 {Sour copies canis). The 

 female, the larger, bores 

 into the skin, there bur- 

 rows, and lays a multi- 

 tude of eggs that soon 

 hatch out, the young run- 

 ning over the surface to 

 repeat the story. The irritation gives rise to intense 

 itching, and an inflammation, with distinct small papules, 

 surmounted by pointed (not flat, as in eczema) vesicles. 



Fig. 27.— Sarcoptes Canis (Gerlach). 



