A 9 year-old male castrated American Bulldog presented to the Cornell University for Animals Cardiology Service on December 11, 2014 for a one week history of polydipsia/polyuria, abdominal distention, lethargy, weakness, and inappetance. An abdominocentesis was performed at the primary veterinarian five days prior to presentation and yielded two liters of straw-colored fluid. Radiographs revealed cardiomegaly and hepatomegaly, which were suggestive of congestive heart failure, so the dog was referred to Cornell. In the five days since the visit to the primary veterinarian, the dog had become increasingly lethargic and inappetant with intermittent increased respiratory effort. In addition, the dog’s abdomen had become distended again to the same extent as before the original abdominocentesis.

On presentation, the patient was quiet, alert, and responsive. The dog was tachycardic (140 bpm) and panting with increased respiratory effort when positioned in sternal recumbency. The heart sounds were muffled and femoral pulses were weak. The abdomen was distended with a marked fluid wave. An electocardiogram was recorded which showed electrical alternans and an echocardiogram revealed a substantial amount of pericardial effusion causing cardiac tamponade. In addition, a heteroechoic mass was found at the right atrio-ventricular junction and a hyperechoic lesion was found associated with the ascending aorta that was consistent either with fibrin accumulation or a mass. The patient had an episode of suspected collapse, so pericardiocentesis was performed and yielded 650ml of dark red fluid. Pericardial fluid analysis revealed a population of large abnormal round cells with cytologic characteristics suggestive of lymphoma. Flow cytometric analysis was performed on the pericardial fluid sample, which identified the abnormal cells as T cells. Based on these results, a diagnosis of cardiac T cell lymphoma was made.

Over the course of 5 days following pericardiocentesis, the patient’s clinical signs resolved completely. A follow-up Oncology appointment was made to discuss treatment options, but the owners elected to continue monitoring the disease and declined further treatment. This presentation will focus on pericardial effusion in a large breed dog and the diagnosis of T cell lymphoma in the heart.