284 DISEASES OF THE SKIN 



emulsion. This should be washed off with warm water the 

 following day to be repeated a week later. 



Psoroptic Mange. — This form of mange usually begins in 

 the most protected parts of the body, such as the mane, tail, 

 sheath, medial surface of the hind limbs, region of the throat, 

 etc. It may, however, spread over the whole body. 



Symptoms. — ^At the point of origin small, circumscribed 

 areas appear partially bald and covered with a scab. The 

 affected parts are itchy causing the animal to bite and scratch 

 them to such an extent that the skin surface becomes raw. 

 The symptoms in general, however, resemble closely those of 

 sarcoptic mange. 



Diagnosis. — An accurate diagnosis is only possible by find- 

 ing the psoroptic mite under the microscope. As these 

 mites are larger and live on the surface of the body they are 

 more readily collected than the sarcoptic mite. Occasionally 

 both forms of mange coexist and lousiness may also be present. 



Prognosis. — The prognosis is more favorable in this than 

 in the sarcoptic form, as the mites are on the surface. How- 

 ever, especially in cold weather, which interferes with the 

 application of the treatment, the case may prove obstinate. 



Treatment. — Treatment is the same as for sarcoptic mange. 



Chorioptic (Symbiotic) Mange. — This form occurs about 

 the fetlocks especially under the flexion of the joint. In 

 neglected cases it may extend over the whole limb and even 

 to the body where it produces symptoms resembling psoroptic 

 mange. 



Symptoms. — ^The symptoms are similar to those of scratches 

 (squamous and crustated eczema). The affected parts are 

 itchy causing the animal to gnaw them and stamp its feet. 

 Such horses are restless, often difficult to shoe and do not 

 thrive well. Heavy draft horses seem most predisposed and 

 the disease is much more severe in winter than during the 

 summer season. 



Diagnosis. — The location and itchiness of the lesions are 

 suggestive. The mites are easily found under the micro- 

 scope. 



Prognosis. — The prognosis is favorable. Under proper 

 treatment a cure is usually attained in about three weeks. 



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