DISEASES OF THE HOKSE. 451 



in and beneath the scurf skin, where it hides and Laj^s its eggs and 

 where its joung are hatched. It is therefore often difficult to find the 

 parasite on the surface, unless the skm has been heated by a tempo- 

 rar}^ exposure to the sun or in a warm room. Even then it maj' 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 wonderfully prolific, a new genera- 

 tion 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 the}^ began to 

 die, and all were dead on the twenty-eighth. 



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

 ing itching of some part of tlie skin (head, mane, tail, back, etc.), the 

 horse inclining himself toward the hand that scratches him, and mov- 

 ing his lips as if himself scratching. The hairs maj^ be broken and 

 rubbed off, but the part is never entirely bald as in ringworm, and 

 tliere 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 b}^ boiling. This maj^ be applied more 

 than once, and should always be repeated after fifteen da3^s, to destroj^ 

 the new brood that may have been hatched in the interval. All har- 

 ness and stable utensils should be similarly treated; blankets and 

 rubbers may be boiled, and the stalls should bo covered with a white- 

 wash of quicklime, containing one-fourth pound of chloride of lime to 

 the gallon. 



Parasite: Sarcoj)te8 mutans. Malady: Sarcoptic acar lasts of 

 folds. — This parasite belongs to chickens, but can live on the skin of 

 the fox and horse as well. A troublesome mange may therefore at 

 times be traceable to the proximity of a chicken roost. The general 

 symptoms and treatment are essentiallv the same as for /Sareoptes 

 scahiei equl. 



Parasite: Psoroptes equl {Dermatocoj^tes equl., Dermatodedes equl). 

 Malady: Psaroptic acarlasls. — This produces the most frequent mange 

 in horses, and as the parasite only bites the surface and lives among 

 the crusts under the shelter of the hair, it is very easily discovered. 

 It reproduces itself with equal rapidity, and causes similar symptoms 

 to those produced by the Sarcojdes. The same treatment Avill suffice 

 and is more promptly effectual. The purifying of the stable must be 



