PARASITES AND PARASITIC DISEASES OF HORSES 45 



When the mites are active under favorable conditions the lesions ex- 

 tend rapidly, and the entire body surface may become involved in 

 about 6 weeks. 



Although they do not propagate themselves except on the bodies 

 of animals, the mites as well as their eggs may retain their vitality 

 for a considerable time off the host animal. When exposed to sunlight 

 in dry places the sarcoptic mites live only a few r days, but in moist, 

 protected places they may live 3 weeks or even longer. Although 

 it is difficult to infect horses experimentally from infested premises, 

 the possibility that the disease may be contracted from such sources 

 should not be overlooked. It is good sanitary practice to clean and 

 disinfect all stables and small inclosures which have been occupied by 

 mangy horses, also all currycombs, brushes, blankets, and other objects 

 used on such horses, before using them for clean animals. Cleaning 

 and disinfecting for sarcoptic mange may be done in the same manner 

 as for lice. 



Treatment. — The common dips, such as lime-sulfur, nicotine, and 

 coal-tar creosote, will kill sarcoptic mites if the dip can be brought 

 into direct contact with the parasites. This method, however, 

 requires thorough, frequent, and persistent applications. From 

 four to six dippings, 5 to 7 days apart, in lime-sulfur or nicotine 

 solution will usually effect a cure in ordinary cases, especially if all 

 affected areas are soaked well with warm dip and scrubbed with a 

 brush just prior to the first dipping. Affected animals should be held 

 in the bath from 2 to 3 minutes. 



Recent investigations have led to the discovery of new acaricides of 

 particular promise for treating certain forms of mange. Among such 

 substances are benzyl benzoate, tetraethylthiuram monosulfide, and 

 benzene hexachloride. It would be wise, therefore, for individuals 

 who are confronted with treating mange in horses to consult a veteri- 

 narian with regard to the possible applications of one of the newer 

 substances. 



Two or more applications, a week apart, of unprocessed crude 

 petroleum will usually eradicate sarcoptic mange, if treatment is ap- 

 plied before the disease becomes chronic. Crude oils, however, often 

 cause the hair to come out and may blister the skin. Crude oil is not 

 a suitable dip for common use on horses, but it is of value in hand 

 treatment for holding mange in check during the winter months when 

 the temperature is too low for dipping. 



Fumigation of many horses with sulfur dioxide has been recom- 

 mended by some European investigators. The Bureau of Animal 

 Industry has conducted some field tests with this method of treatment, 

 but the equipment and methods of application so far devised are too 

 complicated and expensive for general use except w^here large numbers 

 of horses are assembled for treatment under the supervision of a 

 veterinarian. This method of treatment has no advantage over 

 dipping except that it can be used when the temperature is too low 

 for dipping. In applying home treatment or fumigating for mange 

 the medicament has a better chance of reaching the parasites if the 

 hair over and around the lesions is first clipped and singed. 



Cases of sarcoptic mange of long standing, which have been neglected 

 and allowed to develop until the affected skin has become greatly 

 thickened and leatherlike, are usually incurable by any ordinary 



