PARASITES AND PARASITIC DISEASES OF HORSES 



43 



.fiymptoms.—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 slowlv 

 over the body. 



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

 cretion into the wound. A slight inflammation is caused, accom- 

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

 lesions are not sufficiently prominent to attract attention, but the 

 animals rub and bite 

 themselves to relieve 

 the intense itching, 

 and these symptoms 

 should always be in- 

 vestigated to learn the 

 cause. 



As the mites multi- 

 ply, large numbers of 

 small wounds are 

 made in the skin, fol- 

 lowed by the forma- 

 tion of papules, in- 

 creased inflammation 

 and itching, and the 

 exudation of serum. 

 The serum which 

 oozes to the surface 

 becomes mixed with 

 foreign matter and 

 microorganisms, and 

 this mass soon hard- 

 ens into yellowish or 

 gray-colored scabs. 

 The scabs are fre- 

 quently stained with 

 blood. In the early 

 stages the hairs 

 around the lesion 

 may be glued to- 

 gether in a small 

 clump and the nodule 

 or scab may be about the size of a pea. As the mites constantly seek 

 the healthy skin around the edges of the wound, the scab or lesion 

 gradually increases in size. 



Some of the mites migrate to other locations and start new lesions, 

 which extend until they cover large areas. As the disease advances 

 the skin becomes thickened, tumefied, and thrown into wrinkles or 

 folds. Large areas become denuded of hair and covered with thick, 

 adherent scabs. When the disease reaches this stage it is difficult to 

 differentiate it from sarcoptic mange. 



Itching is intense and irritation continues throughout the course 

 of the disease. The skin becomes bruised and raw from the reck- 

 less rubbing against any available surface. The uniform thickening 



Figure 30. — Psoroptic mange mite. 

 100 times) 



Female. (Magnified 



