Abstract
A 9-y-old, spayed female, non-brachycephalic mixed-breed dog was presented with progressive abdominal distension and diarrhea of <24 h duration. An echocardiogram revealed nodular masses in the pericardium and myocardium, particularly near the auricles. Diagnostic and therapeutic pericardiocentesis failed to improve the dog's status, and the owner elected euthanasia. The autopsy revealed numerous nodules within the pericardium, heart base, and myocardium of the left and right ventricles. Histopathology revealed the presence of a neuroendocrine tumor, immunopositive for chromogranin A and negative for synaptophysin and calcitonin, supporting the diagnosis of aortic body tumor with intracardiac metastasis.