2ti PARASITIC DISEASES 



may be seen crawling over the paper. This method of diagnosis 

 should be resorted to in all suspicious cases of skin disease, and 

 before the disease has developed to any great extent. 



The mite that most commonly causes mange in cattle is the 

 Psoroptes commiuiis var. hovis. It may invade the skin in the 

 ditt'erent regions of the body, but it is in the regions of the tail 

 and thighs that the first evidence of the mange is noticed. The 

 animal rubs, scratches, and licks the part. The itching is intense. 

 The hair over the part is lost and the skin appears inflamed, 

 thickened, moist, or covered with white crusts. Cracks and sores 

 may form in the skin. The examination of scrapings from the 

 inflamed skin should be practised in order to confirm the 

 diagnosis. 



Mange in horses may be caused by either psoroptic or 

 sarcoptic mites. Psoroptes communis var. equi seems to be the 

 more common parasite. The itching is intense. The inflamed 

 areas are small at first and scattered over the regions of the 

 rump, back and neck (Fig. G9). After a time the small areas 

 come together and form large patches, and further spreading of 

 the inflammation results from grooming, scratching and biting 

 the skin. Scattered, elevated eruptions on the skin from which 

 the hair has dropped out are first noticed. These parts may 

 show yellowish scabs. Later the skin is thickened, smooth, 

 wriifliled, cracked, or covered with sores. Scrapings made from 

 the inflamed areas of the skin may show the psoroptic mites. 



Mange in Jiogs is comparatively rare. It is caused by one of 

 the sarcoptic mites. The thin portions of the skin are usually 

 first invaded. There are violent itching and rubbing, and small, 

 red elevations occur on the skin in the region of the ears, eyelids 

 or inner surface of tlie thighs, depending on the part first in- 

 vaded. The skin becomes greatly thickened and covered with 

 crusts and scabs. Pus formation and ulceration may occur. 



Treatment of Scab and Mange. — A careful inspection of 

 recently purchased animals that pass through stockyards, or are 

 shipped from sections where scab and mange are common skin 



