Clinical Course and Extended Survival in a Canine Patient with Pericardial Mesothelioma Managed Without Chemotherapeutic Intervention

Background Pericardial mesothelioma is an uncommon and aggressive neoplasm in dogs, typically associated with poor prognosis and limited therapeutic options. Although chemotherapy is frequently used, there is a scarcity of literature describing effective management strategies without chemotherapeutic intervention. This case is reported due to its rarity and the exceptionally long-term survival achieved through non-chemotherapeutic, multimodal management. Case presentation A 7-year-old spayed female Pomeranian presented with acute respiratory distress caused by pericardial effusion. The initial management involved pericardiocentesis and medical therapy, but recurrence of 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. Remarkably, the patient remained clinically stable and maintained a good quality of life for 21 months (628 days) without chemotherapy, supported by regular monitoring and comprehensive symptomatic care. Conclusions This case underscores the clinical importance of individualized, multimodal therapeutic approaches in the management of canine pericardial mesothelioma. It highlights that prolonged survival can be achieved through aggressive effusion control and surgical interventions, even in the absence of systemic chemotherapy. The findings provide valuable insights and potential implications for veterinary clinicians handling similar challenging neoplastic cases.