Computed Tomographic Findings in Cats with Mycobacterial Infection

Objectives: The objective of this study was to describe the CT imaging findings associated with confirmed mycobacterial infection in cats.

Methods: CT images from 20 cats with confirmed mycobacterial disease were retrospectively reviewed. Five cats underwent conscious full-body CT in a VetMouseTrapTM device. All other cats had thoracic CT performed under general anaesthesia, with the addition of CT investigation of the head/neck, abdomen and limbs in some cases.

Results: Mycobacterial infection was seen most frequently in adult (mean age 7.4 years; range 0.6–14 years) neutered male cats (11/20). The most common infections were Mycobacterium microti (6/20) and Mycobacterium bovis (6/20). CT abnormalities were most commonly seen in the thorax, consisting of bronchial (9/20), alveolar (8/20), ground glass (6/20) or structured interstitial (15/20) lung patterns, which were often mixed. Tracheobronchial, sternal and cranial mediastinal lymphadenomegaly were common (16/20). Other abnormalities included abdominal (8/13) or peripheral (10/18) lymphadenomegaly, hepatosplenomegaly (7/13), mixed osteolytic/osteoproliferative skeletal lesions (7/20) and cutaneous or subcutaneous soft tissue masses/nodules (4/20).

Conclusions and relevance: CT of feline mycobacteriosis shows a wide range of abnormalities, often involving multiple organ systems and mimicking many other feline diseases. Mycobacteriosis should be considered in the differential diagnosis of thoracic, abdominal and skeletal disorders in cats.