DISEASES OP THE SKIN. 479 



scrapings on black cardboard and warming, or better by macerating 

 scabs or scrapings in a solution of caustic soda or potash and then 

 examing them microscopically. Like other acari, this is wonder- 

 fully prolific, a new generation of fifteen individuals being possi- 

 ble evety fifteen days, so that in three months the offspring of a 

 single pair may produce generations aggregating 1,500,000 young. 

 The Swrcoptes 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 12 to 14 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 

 presence of the acarus. 



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

 necessary, a brush and the thorough application of tobacco \\ ounces 

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

 than once, and should always be repeated after 15 days, to destroy 

 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 be covered with a white- 

 wash of quicklime, containing one-fourth pound of chlorid of lime 

 to the gallon. 



When there are too many animals to treat by means of hand dress- 

 ings, the lime-and-sulphur dip or the tobacco dip may be used and 

 are very effective, though the cresol dips are fairly effective. These 

 dips may be purchased and made up in the dilution called for on the 

 container. The affected animals may be dipped when the number 

 warrants it and facilities are available; otherwise the dips may be 

 applied with a swab or a spray pump. Directions for constructing 

 a dipping vat may be obtained from the United States Depart- 

 ment of Agriculture on application. Any treatment used should 

 be repeated in the course of 10 to 14 days. If the stables are not 

 disinfected, animals should be removed after treatment and put in 

 clean stables or on clean pasture for at least a month to allow the 

 mites in the infested stables to die. Otherwise the disease may recur. 



