Acute tularemia in three domestic cats

Acute Francisella tularensis infection in 3 domestic cats was presumptively diagnosed on the basis of clinical signs and lesions and confirmed by culturing or immunofluorescent demonstration of the organism. Clinical findings include marked signs of depression, oral/lingual ulceration, regional or generalized lymphadenomegaly, hepatosplenomegaly, panleukopenia with severe toxic change of neutrophils, and hyperbilirubinemia with bilirubinuria. Lesions found at necropsy included icterus, oropharyngeal and lingual ulceration, multiple foci of necrosis in lymph nodes, spleen, liver, and lung, and severe segmental or diffuse enterocolitis. Results of serologic testing for F tularensis was positive in only 1 of the 3 cats. The organism was cultured aerobically from several tissues, including aspirated bone marrow obtained before death in 1 cat. Results of an indirect fluorescent antibody test, performed on fresh and formalin-fixed tissues of all cats, were positive. Because of the severe clinical course, opportunity to evaluate therapeutic regimens was not possible. Until now, confirmed diagnosis of feline tularemia only has been made retrospectively, in instances when cats were suspected to have transmitted infection to human beings in whom the primary diagnosis was made. The findings in this report provide a basis for presumptive diagnosis that will help to minimize public health risk associated with this potentially fatal zoonotic disease.