A 7-year-old male castrated mixed breed dog presented to Cornell University's Soft Tissue Surgery service on October 13, 2016 for evaluation ofan intra-abdominal mass suspected to be associated with the liver by the referring veterinarian. The dog had a 3-month history of weight loss and inappetence and was initially brought to the referring veterinarian in June 2016. His general physical examination was largely umemarkable other than his poor body condition and sarcopenia. Abdominal and thoracic computed tomography with contrast revealed a large (approximately 9cm in diameter) right renal mass. A right nephroureterectomy was performed and excised tissues were submitted for histopathology revealing a renal adenocarcinoma of tubulopapillary type. Renal adenocarcinomas are malignant, locally aggressive tumors with a guarded to poor prognosis due to the high rate of metastasis to the liver, lungs and ipsilateral adrenal gland. Nephroureterectomy is rarely curative; however, human medicine has modeled promising adjunctive therapies.