A Retrospective Histopathological Study on Anthracosis in Captive Wild Birds

Anthracosis, a milder form of pneumoconiosis, is an asymptomatic pathological condition of the lungs generally caused by the accumulation of carbon in the lungs as a result of repeated exposure to polluted air or inhalation of smoke or coal dust particles. The present study reports anthracosis in various species of wild birds presented to the Department of Veterinary Pathology, Kamdhenu University, Navsari-396450, Gujarat, India, from a nearby Zoo during the period from February 2019 to February 2024. A total of 36 lung tissues of wild birds including 10 different families i.e., Psittaculidae, Psittacidae, Pelicanidae, Threskiornithidae, Casuariidae, Struthionidae, Accipitridae, Phasianidae, Gruidae, and Otididae were submitted for histopathological examination, in which 47.22% (17/36) of the birds were found to be affected by anthracosis. Histopathologically, the deposition of coal dust in the lungs was categorized as normal/no anthracosis, minimal, moderate, and severe based on its visualization in a single field of low resolution. Absence of focal deposition of black pigment was considered as normal. Deposition of black pigment at one place (one focus) distributed as minimal, 2-3 foci as moderate, and more than 3 foci as severe. In this study, 19/36 (52.78%) birds were unaffected by anthracosis (Normal), 19.44% (7/36) showed minimal anthracosis, 5.56% (2/36) showed moderate anthracosis, and 22.22% (8/36) showed severe anthracosis. The higher prevalence of anthracosis was noted in birds aged over 10 years compared to the other age groups, suggesting a possible age-related accumulation of inhaled carbon particles.