CHAPTER XVI 



Diseases of the Skin 



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Favus {Baldness or ]]liite Comb) 



This disease of the skin attacks poultry as well as man and 

 the domestic mammals. In mammals it is called tinea favosa 

 or favus. 



Diagnosis. — The disease usually appears first as small 

 gray white spots on the comb, 

 wattles, eyelids and around 

 the ears, that is, on the un- 

 feathered parts of the head. 

 The spots enlarge and run to- 

 gether forming a scaly crust 

 which becomes thicker until in 

 three or four weeks it may be 

 as much as 8 millimeters (^ 

 inch) thick. The scales which 

 make up the crust are often 

 formed in concentric rings, the 

 margins raised and the centers 

 depressed, so that the scale is 

 somewhat cup shaped. When 

 the crust is removed the skin 

 appears irritated and in places 

 the surface is somewhat raw. 

 The disease spreads to the feathered parts of the head, the 

 neck and the region around the vent. The base of the 



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Fig. 52. — Head and neck of a 

 fowl affected with generalized 

 favus. (After Pearson.) 



