Cats are quite resistant to infection with Mycobacterium tuberculosis ; however, they are susceptible to Mycobacterium bovis, Mycobacterium microti, and Mycobacterium avium complex. Lesions in the abdominal organs, such as the mesenteric lymph nodes, are associated with ingestion of contaminated milk or contact with M microti–infected rodents. Infection can rapidly disseminate to other organs, including the lungs and regional lymph nodes. Infected skin or deeper wounds sometimes give rise to tuberculous sinuses. Lesions have a central area of caseous necrosis, usually without calcification.
The tuberculin skin test is considered unreliable in cats. Diagnosis may be assisted by radiography, echography, computed tomography, cytology, and immunologic tests such as lateral flow and interferon-gamma assays. Identification of the organism is necessary to confirm a diagnosis. Antimicrobial treatment can control disease progression.