Apocrine gland anal sac adenocarcinomas (AGASACs) are common tumors in dogs with a moderate to high risk of metastasis to the regional sublumbar lymph nodes. In this lecture, we will discuss preoperative diagnostic tests and clinical staging options. Based on the results of these tests, dogs with AGASAC can then be staged according to whether they have non-metastatic or metastatic AGASAC, and whether metastasis is confined to the sublumbar lymph nodes or to distant sites. A treatment algorithm can then be developed based on the clinical stage, with treatment options including surgery, chemotherapy, radiation therapy, or a combination of these modalities. The prognostic significance of this staging system and individualized treatment protocols will be discussed.