Pulmonic valve myxosarcoma in a dog: Surgical treatment via inflow occlusion

Abstract This case report describes the successful surgical management of a rare pulmonic valve myxosarcoma causing right ventricular outflow obstruction in a 10‐year‐old dog. The patient presented with exercise intolerance and exertional collapse. Echocardiography and computed tomography revealed a large, mobile mass originating from the pulmonic valve, leading to significant outflow obstruction but without myocardial invasion or metastasis. Surgical resection was performed via a left thoracotomy using inflow occlusion and pulmonary arteriotomy, allowing complete tumour removal. Postoperative recovery was mostly uneventful, except for transient metabolic acidosis. Histopathology confirmed a diagnosis of myxosarcoma. The patient remains asymptomatic 9 months postoperatively. This is the first documented case of pulmonic valve myxosarcoma treated surgically with a successful outcome, highlighting a feasibility of surgery in selected cases, in which location and invasiveness of the tumour do not preclude resection.