Resource Library: Anal sac adenocarcinoma, Canine
ANAL SAC ADENOCARCINOMA, CANINE
Anal sac adenocarcinomas are tumors of epithelial origin (most superficial layers) that arise in the anal glands or sacs. They may be found during a routine physical examination and appear as small (0.5 to 3 cm), non-painful, hairless masses associated with the anal sac. They can occur anywhere from the base of the tail to the scrotum (in males) or perineum (in females). They are more common in older, spayed female dogs but have been reported in both male and female dogs, regardless of neutering status. They have the potential to metastasize or spread to the lymph nodes and lungs. Metastasis to the regional lymph nodes has been reported to be 15-50%. Generally, this occurs later in the course of disease. These tumors also have the potential to cause elevated calcium levels in the blood due to the release of a protein called PTH-RP (parathyroid related peptide) from the tumor or its metastases. This can be significant in that elevated calcium levels can damage the patient's kidneys and lead to kidney failure.
The treatment of choice is complete surgical excision of the primary tumor. In an animal with no evidence of metastasis (spread of the tumor), where complete surgical excision has been achieved, use of chemotherapy may be discussed with you.
In an animal with no evidence of metastasis, where complete surgical margins were not attained (that is, all of the tumor cells were not removed completely), follow-up radiation therapy aimed at the surgery site may be recommended.
Mean survival time for all dogs with anal sac tumors is 12 to 15 months. Prognostic factors with anal sac tumors are: size, metastasis and hypercalcemia (elevated calcium in the blood).
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