Mycobacterium pinnipedii causes tuberculous lesions in fur seals, sea lions, and occasionally cetaceans, cattle, humans, and other species. The organism has been isolated in several countries. In pinnipeds, it causes caseous lesions, rarely calcified, with variable amounts of fibrous encapsulation and sometimes draining tracts.
Lesions are usually located in the respiratory tract (peritoneum and lungs) and peripheral lymph nodes, liver, and spleen. In cetaceans, abdominal lymph nodes and the lungs are affected. Aerosols are considered the main route of transmission. Because of the zoonotic risk, precautions should be taken when handling these animals. Serologic tests have been validated in cetaceans.