286 DISEASES OF THE SKIN 



Diagnosis. — ^The diagnosis depends upon finding the mites 

 by scraping freshly infected areas where the scabs are soft, 

 placing the scraping on a piece of black paper in the sun and 

 with a hand lens noting the minute mites which are seen 

 crawling toward the edge of the paper. Obviously a better 

 view may be obtained through the microscope. In very old 

 cases (scabs hard and dry) or if dips have been used the mites 

 are not numerous. 



Prognosis. — ^The prognosis in sheep scab is generally good 

 provided prompt and effective remedial measures are taken. 



Treatment. — ^The treatment consists in dipping the whole 

 flock in some solution which will destroy the parasites. 

 Several solutions are recommended for this purpose: 



(a) Lime-sulphur dip, made by mixing eight poimds of 

 fresh quicklime and twenty-four pounds of sulphur and boil- 

 ing with thirty gallons of water for not less than two hours. 

 All sediment should be allowed to subside before the liquid 

 is placed in the dipping vat. Before using this mixtxu-e it 

 should be diluted with water to make 100 gallons. 



(b) Tobacco-sulphur dip which is made with the extract 

 of tobacco or nicotin. The strength of the mixtiue should be 

 no less than 0.05 per cent, nicotin and 2 per cent, flowers of 

 sulphur. For the first dipping of infected sheep the mixture 

 should contain no less than .07 per cent, nicotin. 



(c) Coal-tar preparation to 50 or 75 parts water. Dipping 

 solutions should be warm (110° F.). 



Sheep should be immersed at least once and should remain 

 in the solution for at least two minutes. It is best to dip 

 after shearing. Ten days later the entire flock should be 

 dipped a second time. After dipping, the flock should be 

 placed where no scabby sheep have been for at least four or 

 five weeks. 



Sarcoptic Mange. — As this form of mange does not usually 

 invade the wool-covered portions of the skin it is found mostly 

 on the head about the lips, nose, face and ears. It is there- 

 fore known as "head scab." More rarely it involves the 

 flexion surfaces of the carpi and tarsi. 



Symptovw. — ^The symptoms are similar to those noted in 

 the horse. Small papules, vesicles, and pustules appear which 



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