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Adenocarcinoma, Anal Sac/Perianal in Dogs

While anal gland/sac cancer (adenocarcinoma) is not common, it is an invasive disease that does not generally have a positive outlook. Usually seen as a rectal growth (mass) on the animal, it also is common to find the disease in the lymph nodes. Due to the type of disease, it is typically malignant and can spread quickly into other areas of the animal's body. There are treatment options available, normally surgical, that can help to improve the animal's chances of survival.

The condition or disease described in this medical article can affect both dogs and cats. If you would like to learn more about how this disease affects cats, please visit this page in the PetMD health library.

Symptoms

The most common sign of anal gland cancer is a rectal mass or tumor. The tumors are often small in nature. In addition to the visible signs of a tumor, animals who are suffering from the disease may be constipated or have difficulty defecating (obstipation), anorexia, polydipsia, and may seem lethargic.

Causes

While this disease is common in dogs, it is not common in cats. There is currently no breed that is a most prone to this type of cancer. The disease is often associated with a hormone imbalance (parathyroid), as it is often found in the anal area. It is also linked with hypercalcemia in the animal's body.

Diagnosis

A fine needle is inserted into the cancerous anal mass (aspirate) and the cells are examined to rule out any other possible conditions. It can be challenging to determine whether the mass is malignant or not, so the needle biopsy is a useful diagnostic test. In some cases an incision and a full biopsy are needed to properly diagnose the mass. Some veterinarians will also use imaging to look at the mass, such as X-rays or ultrasounds.