Anal Gland Cancer in Cats

Published Aug. 25, 2022

What Is Anal Gland Cancer in Cats?

All cats have two anal sacs located between the muscles on each side of the anal sphincter, just past the anal opening/anus. These anal sacs are lined with glands that produce debris, which normally comes out from a small opening on either side of the anus when the cat has a bowel movement.

Anal gland cancer in cats, referred to as anal sac adenocarcinoma, occurs when there is an overproduction of abnormal anal gland cells. While this condition is not common in cats, any cat can develop this cancer.

Symptoms of Anal Gland Cancer in Cats

Common symptoms of anal gland cancer in cats include:

Difficulty having a bowel movement
Constipation
Blood or other abnormal discharge during a bowel movement
A change in the consistency of the feces and/or smaller stool size
Increased litter box use
Swelling or inflammation (redness) around the anal area
Overgrooming of the anal area
Holding the tail in a different position than usual
Decreased appetite
Lethargy

Causes of Anal Gland Cancer in Cats

The exact cause of anal gland cancer in cats is unknown, but there may be a genetic component to this type of cancer. There may also be a link to elevated blood calcium (hypercalcemia) secondary to changes in the parathyroid gland from cancer cells.

How Veterinarians Diagnose Anal Gland Cancer in Cats

A thorough medical history, physical exam, and diagnostic tests will aid a veterinarian in diagnosing anal gland cancer in cats. A physical exam will likely show changes in the anal area that may include:

Swelling
Inflammation
Pain
Bleeding or pus
Ulcers/wounds of the skin surrounding the anus

Common diagnostic tests for anal gland cancer in cats include:

A blood panel (CBC and chemistry), which may show elevated blood calcium, with secondary elevations in kidney values and possible elevations in liver values if the tumor is spreading
Radiographs (x-rays) of the chest, which may reveal tumor spread into the lungs
Abdominal ultrasound, which may show abnormal changes in some of the lymph nodes that are the closest to the anal sacs
A cytology slide of the debris from the anal sacs, which may reveal abnormal anal gland cells
A biopsy for histopathology review of the abnormal anal gland tissue, which will confirm a diagnosis of anal gland cancer

Treatment for Anal Gland Cancer in Cats

Surgical removal of the anal sacs is the preferred treatment option for anal gland cancer in cats. Chemotherapy is another option, but it is not commonly used in cats with anal gland cancer. Radiation therapy is another possible option, but this is also rarely used in these cases.

Surgical removal is not a viable option for anal gland cancer that has spread to the lungs, liver, or other areas of the body. Older cats with other medical issues may also not be good surgery candidates.

Supportive care is indicated for cats who are not good candidates for surgery. It may include:

Appetite stimulant medication

Fluid supplementation (subcutaneous fluids)
Stool softeners (such as lactulose or canned pumpkin)
Enema to help relieve constipation (administered only by a veterinarian)

Recovery and Management of Anal Gland Cancer in Cats

Complications from surgical removal of the anal sacs can include:

Bleeding from the surgery site
Poor healing or infection of the surgery site
Constipation
Fecal incontinence (inability to control a bowel movement)

Because the entirety of the tumor(s) may be difficult to remove, tumor regrowth is another possibility.

Despite surgery and/or chemotherapy, anal gland cancer in cats has a poor prognosis. The main goal of surgery, chemotherapy, and palliative care should focus on keeping the cat comfortable, with minimal suffering. If the pet parent and veterinarian agree that the cat is suffering with a poor quality of life, humane euthanasia may ultimately be considered.

Featured Image: iStock.com/vadimguzhva