Clinical and pathological findings in young Georgia broiler chickens with oculofacial respiratory disease ("so-called swollen heads").

Chickens with swollen heads generally are said to have swollen head syndrome. In this retrospective study, 16 accessions of young chickens during 1992 had "swollen heads." Clinical signs and lesions were accompanied by infection with multiple viruses, bacteria, and Cryptosporidium baileyi. The fact that almost half of the cases of chickens with swollen heads occurred in one broiler-producing company and predictably within 14 days post-vaccination suggests that management factors might be instrumental in inducing the incidence of swollen heads.