A 1-year-old neutered male chinchilla (Chinchilla lanigera) was presented with emaciation and a 1-month history of progressive weight loss. The animal was bright and responsive on clinical examination, but had poor body condition. Serum biochemical analysis revealed elevated alanine amino transferase and alkaline phosphatase. Ultrasound examination was unremarkable. Thoracic radiography showed changes consistent with bullous emphysema and severe pneumonia. Antibiotic therapy was initiated, but the chinchilla died 6 weeks later. Necropsy examination revealed granulomatous lesions in the lungs and liver. Numerous acid-fast bacilli were present in the cytoplasm of macrophages. Sequencing of genetic material isolated from fixed tissue classified the pathogen as Mycobacterium genavense.