THE MITES 105 



When groomed with the brush or currycomb it will manifest its pleasure 

 by protrusion and movements of the upper lip, at the same time leaning 

 toward the brush. This action is not peculiar to mange, however, as it 

 may be observed in any itching skin affection of the horse. The pruritus 

 seems to be greater at night and is always intensified by an increase in 

 the warmth of the body, as by a warm stable or warm clothing. This is 

 probably due to the greater activity of the parasites under such condi- 

 tions. 



Lesions. — The first changes in the skin will be the formation of 

 small nodules, which may be felt by the hand as it is passed over the 

 skin's surface. At these locations small crusts are formed about the 

 tufts of matted hairs, which are easily removed, leaving a moist and 

 reddened surface. From the nodules small papules develop, the epider- 

 mis being raised by the subepidermic serous effusion. These rupture, 

 and the desquamated surface gradually dries, leaving a scaly formation 

 upon the skin. With the extension of these lesions the hair falls out in 

 patches, the affected areas becoming confluent and covered by dry 



Fig. 65. — Burrow of sarcopt in human skin, with eggs and mite (after 

 Osborn, from Furstenburg and Murry; Bureau of Entomology, XJ. S. Dept. 

 of Agr.). 



epidermic scales and thin crusts. Soon following upon this stage the 

 skin thickens and forms into folds, especially over the parts where it is 

 freely movable, as about the throat, neck and breast. When these 

 folds are separated the skin between them is found to be in a raw and 

 purulent condition, bleeding at the slight touch of an instrument or 

 of the finger nail. In neglected cases the body may become almost 

 entirely denuded of hair and the thickened skin covered everywhere with 

 crusts, bleeding fissures, and ulcers, the animal presenting a most 

 miserable appearance (Fig. 66). The alterations in the skin are not all 

 directly brought about by the parasites, being contributed to by the 

 violent rubbing of the animal in its efforts to reheve the itching. Excoria- 

 tions with the formation of hemorrhagic exudations and ulcers are often 

 an accompaniment from this cause. 

 Diagnosis and Development. — With these .symptoms in their early 



