What Is Anal Gland Cancer in Dogs, and What Can I Do About It?

Anal sac adenocarcinoma (AGASACA) is a tumor that forms in the small scent glands just inside your dog’s anus. It can grow quietly before causing obvious signs, and it’s more serious than the common anal gland problems most dogs deal with at some point. The good news: it’s one of the more treatable cancers when caught early.

Here’s what you need to know.

Is it cancer, or just a common anal gland problem?

Most of the time, scooting is not cancer. Dogs scoot for all kinds of reasons: full or impacted anal glands (when the glands get blocked and uncomfortable), anal gland infections, or abscesses (a pocket of infection that forms under the skin nearby). These are common, treatable problems that vets deal with constantly.

Here’s a rough guide to help you read the situation before your vet visit:

• Routine impaction: Scooting, licking at the rear end, a slightly fishy smell. The glands feel full and firm on exam. Relieved quickly with manual expression (your vet empties them by hand).
• Infection or abscess: Swelling, redness, or a visible lump near the anus that may be warm to the touch. Your dog might seem uncomfortable sitting. Treated with antibiotics or, if it ruptures, minor wound care.
• AGASACA: A firm, fixed lump under or near the anus that doesn’t resolve with expression or antibiotics. Your vet may also notice enlarged lymph nodes in the groin or abdomen, and bloodwork might show elevated calcium. Scooting may or may not be present.

The honest truth: you can’t tell the difference at home. If a lump doesn’t go away, or if your dog seems unwell beyond just an irritated rear end, get it checked. A vet can tell the difference fast.

Symptoms: what to look for, and how worried should you be?

The symptoms of anal gland cancer in dogs can be subtle at first, which is why regular vet exams matter so much. Here’s what to watch for:

• A firm, fixed lump near the rectum or anal area: Doesn’t move much when pressed, and doesn’t resolve with anal gland expression or antibiotics. This is the most direct sign and warrants a same-day or next-day vet visit.
• Scooting or excessive licking at the rear end: Common with many anal gland issues. On its own, usually not cancer. But if it persists after routine treatment, it needs further investigation.
• Straining to defecate, or ribbon-like stools: Caused by the tumor pressing on the rectum. If bowel movements have changed alongside any other symptoms on this list, see a vet soon.
• Excessive thirst and urination: This one is easy to miss as cancer-related, but it can be caused by elevated blood calcium (hypercalcemia) from the tumor. If your dog is suddenly drinking much more water alongside any rear-end symptoms, call your vet.
• Lethargy, vomiting, or loss of appetite: Also linked to hypercalcemia. Symptoms that seem completely unrelated to the rear end can actually be the first sign of this cancer.
• Visibly enlarged lymph nodes in the groin: Lumps you’d feel under the skin on either side of the lower belly. A sign the cancer may have spread.

The hypercalcemia connection is worth emphasizing: in some dogs, the cancer causes the body to produce a hormone-like substance that pushes blood calcium levels dangerously high. That elevated calcium affects the kidneys, gut, and nervous system, producing symptoms that can seem totally unrelated to the anal area. If your dog is drinking more, vomiting, and seems off, that’s worth a call to your vet today.

What causes anal gland cancer in dogs?

The exact cause isn’t fully understood, but researchers have identified some consistent patterns. AGASACA is more common in:

• Older dogs, typically over 8 years old (average age around 10 years)
• Spayed females and castrated males equally — historical data suggested a female predisposition, but more recent studies show equal prevalence between spayed females and castrated males. Intact males may have some protective effect from testosterone.
• Certain breeds, including Cocker Spaniels, English Springer Spaniels, German Shepherds, Dachshunds, Cavalier King Charles Spaniels, Alaskan Malamutes, and Golden Retrievers

It’s not caused by chronic anal gland problems, infections, or anything owners typically do or don’t do. This is not a preventable cancer in the way some lifestyle-related diseases are.

How vets diagnose anal gland cancer

If your vet finds a suspicious lump, here’s what the diagnostic process generally looks like:

• Rectal exam: Your vet feels for lumps near or inside the anal canal. This is often where AGASACA is first discovered.
• Fine-needle aspirate (FNA): A thin needle is used to collect a small sample of cells from the lump. It’s quick and usually done without sedation. The sample is examined under a microscope to see if the cells look cancerous.
• Bloodwork: Checks for elevated calcium and assesses overall organ health, especially kidney function.
• Abdominal ultrasound: An imaging scan that lets the vet look at internal structures, particularly the lymph nodes and nearby organs, to check for spread.
• Chest X-rays: To check whether the cancer has spread to the lungs.

Staging (figuring out how far the cancer has spread) directly affects both treatment planning and prognosis. A tumor confined to the gland is a very different situation from one that’s already reached the lymph nodes.

Treatment options

Treatment depends on the stage of the cancer and your dog’s overall health. Your vet or a veterinary oncologist will walk you through the options.

• Surgery: Removing the tumor is usually the first step. When the cancer is caught early and hasn’t spread, surgery alone can be curative. If lymph nodes are involved, those may be removed too.
• Radiation therapy: Often recommended after surgery to reduce the risk of the cancer coming back in the same area. Delivered in sessions over several weeks.
• Chemotherapy: Used when the cancer has spread, or alongside surgery and radiation to target cancer cells that may have traveled elsewhere in the body. It doesn’t cure the cancer in advanced cases, but it can slow progression and improve quality of life.
• Managing hypercalcemia: If blood calcium is dangerously elevated, that needs treatment too, sometimes before anything else. IV fluids and medications are used to bring calcium down.

Prognosis and life expectancy

The honest answer: it varies significantly based on how early the cancer is caught.

• Small tumors that haven’t spread to the lymph nodes, treated with surgery and often radiation: survival times of two years or more
• Lymph node involvement but no distant spread, treated aggressively: often 12 to 18 months
• Distant spread at diagnosis: the focus typically shifts to quality of life rather than cure, and survival is often measured in months

Is anal gland cancer in dogs painful? It can be, particularly as it grows or puts pressure on surrounding tissue. Pain management is an important part of treatment at any stage, and your vet or oncologist will address it directly. For guidance on managing dog pain safely, that’s a helpful reference alongside your vet’s recommendations.

For a broader look at types of dog tumors and how different cancers behave, that’s a useful companion read.

Does pet insurance cover anal gland cancer in dogs?

Treatment for AGASACA, including surgery, radiation therapy, chemotherapy, imaging, and specialist visits, can add up quickly.

Anal gland cancer in dogs is eligible for coverage under a Lemonade accident and illness policy, including diagnostics, surgery, radiation, and chemotherapy, as long as the condition isn’t pre-existing and develops after the 14-day illness waiting period has passed. That means your dog shouldn’t be showing any signs or symptoms before your policy starts or during that waiting period.

If your dog is currently healthy, enrolling now is what gives you coverage if something like this comes up later.

Before we go

A diagnosis of anal gland cancer is genuinely hard news. But it’s also a condition where early detection and treatment can give your dog real, meaningful extra time. If your vet found a lump, or if your dog’s bloodwork showed elevated calcium, you’re already doing the right thing by getting informed. The next step is a conversation with a veterinary oncologist who can give you a clear picture based on your specific dog’s situation.

Frequently Asked Questions

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