Disseminated Mycobacterium avium complex infection in three Siamese cats.

Disseminated infection with Mycobacterium avium complex is described in 3 adult Siamese cats. All cats were the result of father-daughter matings. Clinical signs included anorexia, weight loss, and lethargy. Physical examination revealed pale mucous membranes, lymphadenopathy, splenomegaly, and pyrexia. Nonregenerative anemia was detected in all 3 cats, and macrocytosis was observed in 2. An antemortem diagnosis of mycobacterial infection was made on the basis of identification of acid-fast bacilli in tissue aspirates. The cats died or were euthanatized owing to clinical deterioration, despite antibiotic treatment. Necropsy findings included granulomatous lymphadenitis, enterocolitis, pneumonia, cellulitis, myelitis, and hepatitis. Organisms from the Mycobacterium avium complex were identified in bacteriologic cultures of tissue samples.