Pericardial effusion in a dog due to T‐cell lymphoma of granular lymphocyte type

Pericardial effusions in dogs are most often diagnosed as haemorrhagic and idiopathic. Pericardial effusions secondary to an underlying neoplastic process are infrequently diagnosed, as neoplastic cells are rarely observed in a sample of the effusion. In the present report, we describe a 9‐year‐old dog with pericardial effusion due to T‐cell lymphoma of granular lymphocyte type. Immunophenotyping and molecular clonality PCR were performed to confirm the cytologic diagnosis. To our knowledge, this is the first report of pericardial effusion in a dog due to T‐cell lymphoma of granular lymphocyte type.