Abstract
Chemodectomas (aortic body tumors) are rare, slow‐growing neoplasms arising from chemoreceptor tissue at the heart base in dogs, most frequently reported in brachycephalic breeds; to the authors′ knowledge, their occurrence in nonbrachycephalic large breeds, such as the Alaskan Malamute, is uncommonly documented. An 8‐year‐old intact male Alaskan Malamute (body weight 44.8 kg) was referred with a history of lethargy, inappetence, exercise intolerance, and ascites. Echocardiography confirmed extensive pericardial effusion with cardiac tamponade and a multinodular, irregularly shaped heart‐base mass invading the left atrium, right atrium, left auricle, and aortic root. The dog underwent two pericardiocentesis procedures, yielding 350 and 630 mL of serosanguinous fluid on Days 1 and 15, respectively. The dog died prior to the scheduled 1‐week re‐evaluation. Postmortem examination confirmed a multinodular, irregularly shaped, extensively invasive mass involving all cardiac chambers and the aortic root, with histopathological features morphologically consistent with chemodectoma. This case documents a fatal cardiac chemodectoma in an Alaskan Malamute, contributing to the limited literature on heart‐base tumors in nonbrachycephalic large breeds, and emphasizes the importance of thorough echocardiographic evaluation, serial imaging in dogs with recurrent pericardial effusion, and counseling regarding a guarded‐to‐poor prognosis with extensive cardiac invasion.