Spontaneous ureteral rupture secondary to a ureteral fibrosarcoma in a dog

Abstract A 4‐year‐old, neutered, male Australian shepherd dog was presented with a 2‐day history of anorexia and weakness, with no reported trauma. Clinical examination was unremarkable except for acute abdominal pain. Abdominal ultrasound revealed retroperitoneal effusion and a heterogeneous, ovoid mass in the cranial portion of the right ureter. Antegrade urography and contrast‐enhanced abdominal computed tomography confirmed a tear in the right ureter. Thoracic computed tomography showed no abnormalities. Surgical resection of the affected ureteral segment, including the mass, was performed, followed by an anastomosis of the remaining healthy ureter. Three days postoperatively, a uroabdomen developed due to leakage at the anastomosis site, requiring a right ureteronephrectomy. Histopathological analysis revealed that the mass was consistent with a sarcoma, with immunohistochemistry findings supporting the diagnosis of a ureteral fibrosarcoma. Nine months after surgery, a recheck abdominal ultrasound revealed a heterogeneous vascularised mass at the surgical site, consistent with tumour recurrence.