Disseminated T-cell lymphoma in a free-living white-winged duck (Asarcornis scutulata) under human care

The white-winged duck (Asarcornis scutulata) is an endangered large, stocky anatid species that originates from South-East Asia. We report an adult, 9-year-old male specimen that presented with a 7-month history of intermittent lethargy and pale mucous membranes. Haematology and plasma biochemistry analyses, performed twice at a 6-week interval, revealed anaemia, lymphocytosis and raised renal and hepatic enzyme activities. These findings initially raised clinical suspicion of either avian tuberculosis (ATB), amyloidosis or neoplasia based on species predilection. Initial blood smear evaluation revealed occasional atypical lymphocytes. The duck slowly lost weight over 8 weeks, despite appearing behaviourally normal, prior to rapid deterioration (ie, lethargy and incoordination) resulting in death before euthanasia could be performed. On post-mortem examination, the bird was in poor body condition, with visceral lesions including hydropericardium, an opaquely thickened pericardium, hepatomegaly with dark-to-pale tan capsular and parenchymal mottling, and splenomegaly. On histology and immunohistochemistry, extensive T-cell lymphocytic infiltration was found throughout the pericardium, liver and spleen, with segmental infiltrates within the kidneys and small intestine. Intravascular neoplastic T cells were also seen in large numbers throughout the vascular lumina of the affected organs (indicative of metastatic dissemination). A disseminated lymphoma was favoured over a primary lymphocytic leukaemia due to the lack of lymphocytosis on haematology. This is the first report of disseminated T-cell lymphoma in this endangered duck species.