PART X. 

 DISEASES OF THE SKIN. 



CHAPTER I. 

 NON-PARASITIC SKIN DISEASES. 



Examination. Careful methods are required for an accu- 

 rate diagnosis of skin diseases. Small diseased areas and 

 the larger parasites, if not very numerous, may easily be 

 overlooked in long-haired individuals, or in birds. 



In the majority of cases a microscopic examination is 

 necessary to determine if a skin disease is parasitic or non- 

 parasitic. If the former, it is necessary to identify the 

 parasite in order to give the proper prognosis and treatment. 



Some few cases present certain rather characteristic 

 features which indicate the real nature of the disease but 

 the only accurate diagnostic method is by the use of the 

 microscope. The larger parasites may be identified with a 

 reading glass; the mange mites can be seen with a micro- 

 scope, using low power, while high power is necessary to 

 identify some of the vegetable forms. 



Microscopic Examinations. With a small, sharp curette 

 scrape deeply into the skin at a point where the disease 

 process is active until a mass of moist scrapings the size 

 of a grain of wheat is obtained. Transfer this mass directly 

 to a slide and moisten it with a drop of water. Put on a 

 cover-glass and press down with a rotary motion to evenly 

 distribute the material to the proper density. By this 

 method animal parasites remain active, and their movements 

 readily indicate their presence. For vegetable parasites 

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