By Dr. Becker
Thankfully, cancer of the anal glands, also called adenocarcinoma, is not a common disease in dogs and is even more rare in kitties. However, when it does occur, it is invasive and often carries a very poor prognosis.
Anal gland cancer appears as a rectal mass and is frequently also found in the lymph nodes. In most cases, the tumor affects only one anal gland, but occasionally both glands are involved. This type of cancer is typically malignant and spreads quickly to other locations in the animal’s body, including the liver and lungs.
As with most cancers, there is no known cause for anal gland tumors. However, the disease is often associated with a parathyroid hormone (PTH) imbalance and is also linked with hypercalcemia, a condition in which blood calcium levels are abnormally high.
Symptoms and Diagnosis of Anal Gland Cancer
The most common sign of anal gland cancer is a rectal mass or tumor that your veterinarian can feel during an examination. Sometimes, there is a large visible swelling on the anal region of your dog or cat.
Other symptoms can include constipation; difficulty pooping or passing urine; thin, ribbon-like stools; and arching of the back. If the tumor has caused hypercalcemia, additional signs can include increased thirst and urination, decreased activity, loss of appetite, weight loss, vomiting, muscle weakness, and sometimes a slow heart rate.
Diagnosis of an anal gland mass is made by digital rectal palpation by your veterinarian. Confirmation of the type of tumor requires a fine needle aspirate or tissue biopsy. Other tests will include a complete blood count (CBC), serum chemistry profile, parathyroid hormone testing, urinalysis, chest X-rays to check for metastasis, and an abdominal ultrasound to determine whether the cancer has spread into the abdomen.
The recommended treatment for anal gland cancer is surgery to remove the tumor as well as a wide margin of tissue around it to try to insure no tumor cells are left behind. Unfortunately, in over half of animals with anal gland tumors, the cancer has metastasized to nearby lymph nodes, which may also need to be surgically removed.
If the cancer has spread to the lungs, liver, or other organs, surgery may be palliative rather than curative, meaning it will be done simply to relieve straining in pets that have bowel issues. In those cases, surgery may not improve survival time.
Sometimes, chemotherapy is given after surgery in an effort to kill any remaining cancer cells. Unfortunately, even if there is no evidence the cancer has spread at the time of diagnosis, it’s possible that tumor cells are already circulating throughout the pet’s body, with the potential to establish new tumors in other organs.
Radiation therapy is also sometimes used to treat tumors that could not be removed by surgery or that were not entirely removed.
Risks associated with anal gland surgery include bleeding during the procedure, permanent nerve damage that can lead to urinary incontinence or fecal incontinence, and difficulty defecating.
The outlook for a pet with anal gland cancer depends to a large extent on how severe the disease is at time of diagnosis. When the cancer has not spread to other organs and the tumor can be completely removed with surgery, the prognosis is much better than for pets with metastasized cancer or a tumor that cannot be completely excised.
Unfortunately, estimates are that by the time 50 to 80 percent of anal gland tumors are diagnosed, the cancer has spread. Pets with metastasized cancer are estimated to have a median survival time after surgery of 6 months. Those without metastasis have a median survival time between 15 and 16 months.
Certainly holistic practitioners want to see these patients sooner rather than later, as an adjunctive protocol can often extend the quality and quantity of life for these pets. I have used IV vitamin C therapy, aggressive oral antioxidant protocols, Chinese herbs, and turmeric many times to help support patients with this devastating diagnosis. Rectal ozone therapy may also be of benefit to these patients.