PARASITES OF THE SKIN. 451 



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

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

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

 usually applied to effect a cure. 



ANIMAL PARASITES OF THE SKIN. 



Acariasis, or mange. — This affection is due to the irritation of the 

 skin caused by the presence of nearly microscopic acarus, or mite. 

 The disease varies, however, according to the species of acarus which 

 infests the skin, so that we must treat of several different kinds of 

 acariasis. 



Parasite : Sarcoptes scabiei equi. Malady : Sarcoptic acariasis. — 

 This is the special Sarcoptes of the horse, but under favorable condi- 

 tions it can be transmitted to ass and mule, and even to man, and may 

 live indefinitely on the human skin. The mite is nearly microscop- 

 ical, 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 parasite 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 acarus will be found in the center of a 

 minute papule caused by its bite. Like other acari, this is wonder- 

 fully 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 generations aggregating 1,500,000 young. The 

 Sarcoptes have less vitality than the nonburrowing acari, as they 

 die in an hour when kept apart from the skin in dry air at a heat of 

 145° F. 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, when they began to die, and all were dead 

 on the twenty-eighth. 



Symptoms. — The symptoms are an incessant, intolerable, and in- 

 creasing 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 ring- 

 worm, 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 intense itching and the 

 discovery of the acarus. 



Treatment consists in the removal of the scabs by soapsuds, and, if 

 necessary, a brush and the thorough application of tobacco 1| ounces 

 and water 2 pints, prepared by boiling. This may be applied more 



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