46 



CIRCULAR 148, U. S. DEPARTMENT OF AGRICULTURE 



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 mea- 

 suring about one-for- 

 tieth and the male 

 about one-fiftieth of an 

 inch in length (fig. 30). 

 The entire life cycle is 

 passed on the host ani- 

 mal. Each female may 

 deposit from 15 to 24 

 eggs, which hatch in 3 

 to 4 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 cannot be 

 depended on to destroy 

 the eggs. Some of the 

 eggs may hatch after 

 dipping, thus forming a 

 new generation of mites. 

 To effect eradication it 

 is necessary to give a 

 second dipping after 

 hatching is completed 

 and before the young 

 mites reach maturity 

 and begin laying eggs. 

 It is evident that the interval between the first and second dippings 

 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 

 by an intense itching. In the early stages of the disease the lesions 

 are not sufficiently prominent to attract attention, but the animals rub 



Figure 30. — Psoroptic mange mite, 

 nified 100 times.) 



Female. (Mag- 



