Case Report: Clinical course and extended survival in a canine patient with pericardial mesothelioma managed without chemotherapeutic intervention

Pericardial mesothelioma is a rare and aggressive neoplasm in dogs, typically associated with a poor prognosis and limited treatment options. While chemotherapy is commonly employed, there is limited literature describing successful management without chemotherapeutic intervention. This case report describes a 7-year-old spayed female Pomeranian presenting with acute respiratory distress caused by pericardial effusion. Initial management included pericardiocentesis and medications, but recurrence of the effusion necessitated surgical intervention. Subtotal pericardiectomy was performed, and malignant pericardial mesothelioma was confirmed histopathologically. A thoracic port was implanted postoperatively for ongoing effusion management. The patient remained clinically stable and maintained a good quality of life for 628 days without chemotherapy, supported by regular monitoring and comprehensive symptomatic care. This case highlights that prolonged survival may be achieved through aggressive effusion control and surgical intervention in dogs with pericardial mesothelioma when systemic chemotherapy is not feasible.