Ureteral Haemangiosarcoma in a Dog: Rare Primary Tumour With Unusual Metastasis to the Contralateral Kidney.

A dog (neutered male, 11 years old, Labrador retriever) underwent abdominal ultrasound, which revealed a 7 cm diameter tumour (caudal region of the left kidney). The animal showed symptoms of weight loss, apathy, haematuria, and abdominal pain. A computed tomography (CT) scan confirmed the presence of a tumour originating from the ureter. Following surgery to remove the ureter with the attached kidney, a histopathological examination was performed. The tumour was classified as a haemangiosarcoma. After the initial recovery, 2 months after surgery, the dog was diagnosed with a tumour in the other kidney. A fine needle biopsy was carried out. A haemangiosarcoma metastasis was suspected. Neoplasms of the ureter are a rare pathology. This is the first case in which metastasis to the second kidney has been confirmed.