Presumed Mycobacteriosis in Laboratory Zebra Finch (Taeniopygia guttata)

Husbandry staff noticed a research-naïve, young-adult, female finch tossing its head back intermittently. A second finch exhibiting similar signs was reported a few days later. Postmortem necropsy and histopathology with hematoxylin and eosin and acid-fast staining on the first finch revealed the presence of acid-fast organisms in several organs. After presumptive diagnosis of mycobacteriosis, all remaining finches housed in the same room as the first underwent necropsy and histology. Three additional finches were positive for Mycobacterium-like acid-fast organisms. Incidental findings of megabacteriosis were noted histopathologically on 2 other finches.Abbreviation: MAC, Mycobacterium avium complexMycobacteriosis has a worldwide distribution and is found often in free-living birds, poultry, and wild birds. Several natural cases of mycobacteriosis have occurred in pet birds, including canaries (Spinus cucullatus), Eurasian goldfinches (Carduelis carduelis), and Zebra finches (Taeniopygia guttata).⁶ Reports regarding cases of mycobacteriosis in the laboratory animal research setting are scarce. The most common agents of avian mycobacteriosis are Mycobacterium avium intracellulare, one of the group of bacteria known as Mycobacterium avium complex (MAC), and Mycobacterium genavense, a known cause of mycobacteriosis in birds and mammals.^1,5,9-11 In addition, immunocompromised humans can be infected with MAC.^3,6,10 Mycobacteria are saprophytic, aerobic, and common in soil and the environment. These organisms can be transmitted by ingestion of soil or cage litter contaminated by fecal matter from infected birds.^1,2 The most common clinical signs in affected birds are depression, lethargy, and feather erection or fluffing, as are typical for most sick birds.^9,11 Neurologic signs, if they occur, can include imbalance and the inability to walk or fly normally.⁹