Palliative Debulking of an Aortic Body Tumour With Right Atrial Invasion in a Dog Under Partial Cardiopulmonary Bypass.

BACKGROUND: Aortic body tumours are uncommon heart-base neoplasms in dogs, and intracardiac extension causing clinically significant right atrial obstruction is rarely described. CASE PRESENTATION: A 7-year-1-month-old, 15.2-kg, castrated male French Bulldog was evaluated for 2 weeks of lethargy, hyporexia, exercise intolerance, abdominal distension, and polydipsia. Transthoracic echocardiography revealed severe right-sided cardiac enlargement and a heterogeneous right atrial intracavitary mass (3.2 × 3.1 cm) suspected to arise from the heart base, with tricuspid regurgitation (maximal velocity 4.03 m/s). Abdominal ultrasonography showed hepatic venous congestion and marked ascites; fluid was a modified transudate. Medical therapy failed to resolve ascites, and surgical debulking was performed on Day 7 under partial cardiopulmonary bypass. The mass was firmly adherent to the atrial septal aspect and could not be completely excised. Postoperatively, ascites and clinical signs resolved, right-sided cardiac enlargement decreased, and tricuspid regurgitation was no longer detectable; the dog was discharged on Day 14. A recurrent right atrial mass was documented on Day 360 without recurrence of right-sided heart failure. The dog died on Day 390 from pancreatitis-associated biliary obstruction and multiple organ failure. Necropsy confirmed an aortic body tumour with intracardiac extension into the right atrium and pulmonary metastasis with tumour emboli. CONCLUSION: Partial cardiopulmonary bypass-assisted palliative debulking may temporarily relieve life-limiting intracardiac obstruction in carefully selected dogs; however, this approach is high-risk and non-curative, and its contribution to long-term survival remains uncertain because postoperative toceranib therapy and the natural behaviour of the tumour may also have influenced the clinical course.