An 11 year old, female spayed Huskey mix was referred to the Oncology Service at the Cornell University Hospital for Animals on 01/08/03, for further treatment after incomplete surgical resection of an anal sac adenocarcinoma. The dog initially presented to the referring veterinary (RDVM) for evaluation of polyuria, and polydipsea. During physical examination a left perianal mass was detected by rectal palpation. Anal sac adenocarcinoma was suspected. Thoracic radiographs and abdominal ultrasound were performed and were negative for metastasis. An incisional biopsy of the perianal mass was performed and the tissue submitted to the Cornell histopathology service. A diagnosis of apocrine adenocarcinoma of the anal sac was confirmed.