Pathology of experimental avian cholera in mallard ducks.

Mallard ducks (Anus platyrynchos) challenged with two isolates of Pasteurella multocida developed either acute or chronic lesions, depending on the isolate of P. multocida and the inoculation dose. Ducks that died acutely of avian cholera had lesions of a hemorrhagic septicemia with widespread vascular damage and focal necrosis in liver, spleen and other organs. Ducks that survived challenge developed chronic lesions in a variety of organs, including brain, lung, air sacs, joints, and eyes. Some surviving ducks sequestered bacteria within these loalized lesions and may be potential "carrier" birds. The possible pathogenesis of P. multocida infection in ducks is discussed.