DISEASES OF POUI<TRY. 



189 



develops in round or concentric deposits, raised at the 

 border and depressed at the center, giving to the spots 

 a cup-shaped appearance. The crust increases in 

 thickness until in the course of a month it may be 

 one -fourth inch or more in depth. It is then of a 

 dirty -white color, scaly and irregular on the surface. 

 When the crust is removed the skin is seen to be irri- 

 tated and slightly 

 excoriated. The 

 disease extends 

 from the bare parts 

 of the head to the 

 parts of the body 

 covered' with 

 feathers. The 

 neck, the region 

 about the vent, and 

 the adjoining sur- 

 faces are soon in- 

 vaded. The 

 feathers become 

 dry, erect and brit - 

 tie, they break and 

 fall off leaving the 

 skin denuded and 

 c overed w i th 

 crusts, which are 

 often cup -shaped, having in the center the depression 

 in which the feather was fixed. 



At first the general health of the bird is not visibly 

 affected, it appears bright, eats well and conducts it- 

 self as usual. After a time, however, when a con- 

 siderable area has been invaded, it manifests weak- 

 ness, loses flesh, its appetite becomes irregular and it 



'Head and neck of a fowl affected 

 with generalized favus. 



