PARASITES AND PARASITIC DISEASES OF HORSES 



43 



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 de- 

 velop until the af- 

 fected skin has become 

 greatly thickened and 

 leatherlike, are usu- 

 ally incurable by any 

 ordinary 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 compara- 

 tively 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 meas- 

 uring a b o u t one- 

 fortieth and the male 



Figure 30. 



-Psoroptic mange mite. 

 1 00 times ) 



Female. (Magnified 



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 maturity, 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. 



Symptoms. — Psoroptic mange may start on any part of the body 

 covered thickly with hair, but the first lesions usually appear on the 

 head under the foretop, on the top of the neck around the mane, or 

 on the rump. From the starting point the disease spreads slowly 

 over the body. 



The mites prick the skin and probably introduce a poisonous secre- 

 tion into the wound. A slight inflammation is caused, accompanied 



