Early detection and aggressive treatment are essential in the successful management of this tumor. Hypercalcemia of malignancy is seen in some cases as a paraneoplastic syndrome and may contribute to presenting clinical signs. Early detection and aggressive treatment are essential in the successful management of this tumor, which emphasizes the importance of a rectal examination as part of a routine physical examination in all animals. Treatment typically requires a multimodal approach involving surgery, radiation, and, potentially, chemotherapy.
Anal sac adenocarcinoma occurs primarily in older dogs, with an average age of Owners or groomers may be the first to notice perineal swelling or discomfort. The primary anal sac mass or enlarged iliac lymph nodes may cause constipation, obstipation, tenesmus, dyschezia, or ribbonlike stools.
Earlier clinical signs are not always noticed by owners but can include scooting and excessive licking of the perineal area. Polyuria, polydipsia, anorexia, and lethargy can be seen secondary to hypercalcemia of malignancy, a common sequela of anal sac adenocarcinoma, although not all dogs with hypercalcemia will display such clinical signs. Anal sac adenocarcinoma can also be an incidental finding on rectal examination in a high proportion of affected dogs.
In most cases, a physical examination will reveal a perianal mass associated with one or both anal sacs. Occasionally, a mass may not be appreciated externally, so a thorough digital rectal examination is advised in all dogs. Enlarged iliac lymph nodes may be palpable on rectal examination in cases of metastatic or reactive lymphadenopathy, but this enlargement can be difficult to detect in larger dogs or in cases in which the enlargement is subtle.
The recommended work-up for a dog with an anal sac mass includes a minimum database complete blood count, serum chemistry profile, urinalysis to assess the animal's overall health and identify whether paraneoplastic hypercalcemia is present.
