Differences in Familial Incidence of Mortality from “Blue Comb” Disease

THE diagnosis of blue comb on the basis of clinical symptoms, and gross and microscopic lesions, is fairly definite when the disturbance involves several birds in a population. It is much less so when only an individual bird is available for autopsy and the case history does not indicate a generalized flock condition. Blue comb, as a specific disease entity, has been recognized for several years and can cause considerable loss in the form of mortality, reduced production, and often from the failure of laying flocks to regain previous levels of performance. It apparently is not limited to any age group or season of the year, although many of the outbreaks occur among maturing pullets during the hot summer weather. CASE HISTORY Blue comb, as such, has not been a problem in the departmental flock at Cornell University for several years. About 1940, this disease affected newly-housed White Leghorn pullets, . . .