42 CIRCULAR 14 8, U. S. DEPARTMENT OE AGRICULTURE 



sulphur, 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 applica- 

 tions. From four to six dippings, five to seven days apart, in lime- 

 sulphur 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 two to three minutes. 



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

 petroleum will usually eradicate sarcoptic mange, if treatment is 

 applied 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. Crank-case 

 drainings may be substituted for crude petroleum, but such oils also 

 cause loss of hair and often blister the skin. 



Fumigation of mangy horses with sulphur dioxide has been recom- 

 mended by some European investigators. The Bureau of Animal 

 Industry has conducted some field tests with this method of treat- 

 ment, but the equipment and methods of application so far devised 

 are too complicated and expensive for general use except where large 

 numbers of horses are assembled for treatment under the supervision 

 of a veterinarian. Apparently this method of treatment has no dis- 

 tinct 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 reach- 

 ing 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 ordi- 

 nary method of treatment. In cases of suspected mange prompt and 

 vigorous action should be taken, as the disease can be eradicated in 

 the early stages at comparatively low cost. 



PSOROPTIC MANGE 

 PSOROPTIC MANGE MITE 



The mite (Psoroptes communis equi) which causes psoroptic 

 mange lives on the surface of the skin and does not form burrows. 

 Psoroptic mites are slightly larger than sarcoptic mites, the mature 

 female measuring about one-fortieth and the male about one-fiftieth 

 of an inch in length. (Fig. 30.) The entire life cycle is passed on 

 the host animal. Each female may deposit from 15 to 24 eggs, 

 which hatch in three to four days. The young mites reach matur- 

 ity, mate, and the female deposits eggs in from 10 to 12 days. 



Dipping, if properly done, kills all psoroptic mites, but can not be 

 depended on to destroy the eggs. Some of the eggs may hatch after 

 dipping, thus forming a new generation of mites. To effect eradica- 

 tion it is necessary to give a second dipping after hatching is com- 

 pleted and before the young mites reach maturity and begin laying- 

 eggs. It is evident that the interval between the first and second dip- 

 pings should be from 10 to 12 days. 



