Gross and microscopic lesions in young chickens experimentally infected with Salmonella enteritidis.

One-day-old and 7-day-old specific-pathogen-free chickens were orally infected with a field isolate of Salmonella enteritidis phage type 13A. Chickens were sequentially euthanatized at various intervals until 42 days of age, and selected tissues were collected for microscopic evaluation. Eleven of 53 chickens (21%) infected at 1 day of age and 2 of 28 chickens (7%) infected at 7 days of age died. Gross and microscopic lesions were more frequent and severe in chickens infected at 1 day of age and in chickens that died (almost all of these were 1-day-infected as well). Lesions were characterized by mild to severe fibrinous pericarditis, airsacculitis, perihepatitis, peritonitis, cecal cores, and enlarged, firm yolk sacs. Gross the microscopic lesions were present from postinoculation day 2 until termination of this study.