Abstract
Broiler cases of swollen head syndrome (SHS) occurring at three different farms and showing respiratory symptom, swollen heads and severe depression were studied pathologically. Atnecropsy affected chickens showed the swollen head and eyelids due to facial cellulitis with caseous exudate in the air space of the cranial bones but no exudate in the lumen of the infraorbital sinus and the nasal cavity. Microscopy revealed chronic fibrinopurulent inflammation with granulomas in the air space of the cranial bones, middle ears and facial skin. Conjunctivitis and tracheitis with infiltration of lymphocytes and plasma cells with germinal centers were observed. The E. coli isolate from the wattle of an affected chicken was inoculated intramuscularly (107 CFU) into 2-weeks-old SPF chicks, and acutefibrinopurulent pericarditis and serositis, but no SHS lesions were produced.
