Experimental reproduction of endocarditis with Pasteurella gallinarum in mature leghorn chickens

The pathogenicity of Pasteurella gallinarum for mature leghorn chickens was investigated by inoculating thirty 52-week-old chickens intravenously with live P. gallinarum. Each chicken was inoculated once daily for 5 days at one of three different dosage levels with either the type strain ATCC 13361 or a field isolate from a chicken with endocarditis. Chickens were necropsied after death or euthanasia. Valvular endocarditis was present in seven chickens given the field isolate and five chickens given the type strain. Other lesions detected were myocarditis, hepatic and splenic infarcts, nephritis, pneumonia, and encephalitis. At necropsy, P. gallinarum was reisolated from hearts, livers, spleens, lungs, kidneys, and blood. Controls injected with sterile broth had no lesions of endocarditis, nor was P. gallinarum isolated from them. The results confirm the pathogenicity of P. gallinarum for the heart valves of mature chickens.