070 



Acarus Mange. 



'^y^ 



without exception with their heads directed towards the base 

 of the cavity (Fig. 153). The constant increase of the mites and 

 their eggs and larvae cause a sac-like dilatation and lengthening 

 of the hair follicle and sweat gland, whereby the epithelial layer 

 of the hair follicle and later on also the hair papilhie are caused 

 to atrophy. In consequence the hairs will break off in the hair 

 follicles or become loosened from the papillae. The irritation pro- 

 duced by the numerous mites further causes a dilatation of the 

 neighboring blood vessels as well as an increased formation of 

 epidermal cells, whereupon an accumulation of horny masses 

 and even of horny balls and horny plugs may occur, and many 

 of the orifices of the hair follicles are blocked up by them. There 

 occurs an increased new-formation and desquamation of epi- 

 dermal cells on the surface of the skin between the openings of 

 the hair follicles. Later on an invasion of 

 staphylococci takes place (Staphylococcus 

 pyogenes albus), probal)ly in consequence 

 of dilatation and bulging of the hair bulbs, 

 especially of the hair follicle. These in- 

 crease on the walls of the hair bulbs and 

 sebaceous glands, gradually penetrate 

 downwards and cause an inflammatory pro- 

 cess in the hair follicles and sweat glands 

 and in their neighborhood, finally leading to 

 the formation of small and in some cases 

 large abscesses ; suppuration of the wall of 

 the hair follicle or sebaceous gland does 

 not, however, occur. The formation of 

 pustules occurs from a secondary infec- 

 tion with staphylococci, which in its turn 

 may lead to a general septic infection or 

 intoxication (Gmeiner). 



The further extension of the eruption 

 on the same animal results from licking 

 and rubbing, as well as from the fact that 

 the mites come out of the originally 

 diseased hair follicles and penetrate into the neighboring 

 healthy ones, or that the healthy parts of the body of the ani- 

 mal come in contact with objects previously contaminated by 

 their pustular contents. The spread of the eruption and still 

 more the formation of pustules are aided by oft-repeated rub- 

 bing of the skin with irritant substances, and even by very 

 often repeated washings. It is peculiar that the disease may 

 remain limited for a long time to small areas in individual ani- 

 mals, or that it may assume a pustular character only late or 

 sometimes not at all. 



Fig. 153. Acarus mite in 



a hair follicle. Magnif. 



150. (After Megnin.) 



Symptoms. The symptoms of acariasis differ in part ac- 

 cording to the breed of the animals, but great variations may 

 be noticed even in animals of the same breed. 



