438 



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microscope, is unaffected by acetic acid, alcohol, ether, or oil of tarpen- 

 tine, while the cells are turned bluish by iodine. For treatment, re- 

 move the hair and apply tincture of iodine or corrosive sublimate lotion, 

 as advised under the last paragraph. 



Parasite: Mlcrosporon Furfur. Malady: Parasitic pityriasis. — 

 This ^jttacks the horse's head where the harness presses, and leads to 

 dropping of the hair, leaving bald patches covered with a branlike 

 scruf, without any eruption, heat, tenderness, swelling, or rigidity of 

 the skin. A lotion of carbolic acid, 1 dram, and water, 2 J ounces, is 

 usually applied to effect a cure. 



ANIMAL PARASITES OF THE SKIN. 



Acariasis: Mange. — This affection is due to the irritation of the skin, 

 caused by the presence of a nearly microscopic acarus or mite. The 

 disease varies, however, according to the species of acarus which in- 

 fests the skin, so that we must treat of several different kinds of acari- 

 asis. 



Parasite: Sarcoptes equi. Malady: Sarcoptic acariasis. — This is 

 the special sarcoptes of the horse, but under favorable conditions it 

 can be transmitted to ass and mule, and even to man, and may live 

 indeilnitely on the human skin. The mite is nearly microscopical, but 

 may be detected with a magnifying lens among moving scurf taken 

 from the infected skin. Like all sarcoptes, it burrows little galleries in 

 and beneath the scurf skin, where it hides and lays its eggs and where 

 its young are hatched. It is therefore often difficult to find the para- 

 site on the surface, unless the skin has been heated by a temporary 

 exposure to the sun or in a warm room. Even then it may be needful 

 to tie the scab on the human arm till a pricking is felt, when the aca- 

 rus will be found in the center of a minute papule caused by its bite. 

 Like other acari this is wonderfully prolific, a new generation of fifteen 

 individuals being possible every fifteen days, so that in three months 

 the offspring of a single pair may produce a generation of 1,500,000 

 young. The sarcoptes have less vitality than the nonburrowing acari, 

 as they die in an hour when kept in dry air apart from the skin at a 

 heat of 1450 P. They live twelve to fourteen days apart from the 

 skin in the damp air of a stable. On a piece of damp hide they lived 

 till the twenty-fourth day, but were dead on the twenty-eighth. 



The symptoms are an incessant, intolerable, and increasing itching of 

 some part of the skin (head, mane, tail, back, etc.), the horse inclining 

 himself toward the hand that scratches him, and moving his lips as if 

 himself scratching. The hairs may be broken and rubbed off, but the 

 part is never entirely bald as in ringworm, and there may be papules 

 or any kind of eruption or open sores from the energy of the scratching. 

 Scabs of any thickness may form, but the special features are the in- 

 tense itching and the discovery of the acarus. 



