Canine Cancer – Identifying Lumps, Bumps and Tumors

It’s not uncommon for a pet owner, during the course of their pet’s lifetime, to feel a small bump or mass on their dog’s body.

black dog on rustic wood floor

I imagine the moment goes something like…

Hmm, what’s that?
[takes a closer look]
Is this new?
[looks again]
[panic attack, fainting, running to vet, possibly all at the same time]

Ok, I’m dramatizing, but cancer is a dreaded word for pet owners, and not without reason. But not all cancer is the same, and not every lump is cancer.

The general term for any lump forming on your pet’s body is a tumor. A tumor is simply an abnormal growth of cells. People’s minds are quick to jump from tumor to cancer, and especially with malignant cancer- the invasive, aggressive and deadly form of cancer that spreads and overwhelms other organs and lymph nodes.

But there are also tumors, including certain warts and masses, which are not aggressive and generally do not spread.

Is it Cancer?

Dogs can sprout a variety of lumps, bumps, and skin growths, especially as they get older. Fortunately, most are merely unsightly or messy rather than harmful.

Dog warts or cutaneous papillomas

These cauliflower-like tumors typically show up on the head, feet, ears, and genitalia, but some dogs develop them everywhere and anywhere.

Typically benign, papillomas are generally caused by something called sebaceous gland hyperplasia. These tumors often turn up in middle-aged or older dogs and can come back if removed.

Canine viral papilloma

Not Cancer

canine viral papilloma

“Canine Viral Papilloma”, by Joel Mills, CC BY-SA 3.0, via Wikimedia Commons

Also know as a wart, these benign, flat, raised, skin masses are caused by the papillomavirus and are commonly found in the oral cavity and on the paws and digits, though they can form anywhere on the body, including on the eyelids. Young dogs occasionally develop these growths, only to have them all disappear a few months later.


Dogs can get skin cancer too. Melanomas can occur anywhere there is melanin – or pigment – including the eyes, feet and mouth.



histiocytoma on a dogs ear

“Histiocytoma” by Joel Mills, CC BY-SA 3.0 via Wikimedia Commons

These masses are red in color and often have a button like shape, giving them the somewhat whimsical nickname, “button tumors.” They are most often found on the head, ears, and legs of puppies and on dogs less than four years old. These can disappear on their own within a 8 to 12 weeks, but dogs will lick them constantly which cause increased inflammation and redness.

These tumors are pretty rare, and are sometimes misdiagnosed as something more serious, so work with your vet to get a second opinion if you aren’t certain and find a qualified pathologist.

Lipomas or fatty tumors

Not Cancer
These soft tumors are generally found around the neck, chest, abdomen, and legs of dogs over 8 years old. While benign, they can grow quite large and interfere with organs or irritate your dog, which can be reason enough to look into having them removed.



Lymphoma in a Golden Retreiver

“Lymphoma in golden” by Joel Mills, CC BY-SA 3.0 via Wikimedia Commons

A type of malignant cancer that usually originate in the lymph nodes, though it can appear in any tissues in the body. Multicentric lymphoma is the most common type of lymphoma found in dogs, and is characterized by painless swelling of the lymph nodes.

Sebaceous gland tumor or cysts

Not Cancer
These benign, wart-like skin masses can form on any part of a dog’s skin. They are very common in older dogs and typically appear on the hair, neck, ears, and legs.

Mast cell tumor


mast cell tumor on a dogs side

“Mast cell tumor side” by Joel Mills, CC BY-SA 3.0 via Wikimedia Commons

This is a malignant skin mass in dogs and presents with a variety of appearances. While frightening to encounter, there are different grades of mast cell tumors. With lower grades, surgical excision is likely curative, though higher grade mast cell tumors have a poorer prognosis.

Fibrovascular Papilloma

Not Cancer
Also known as a skin tag. This skin mass is finger-like in appearance and have a distinctive pedunculated neck at the skin connection. They are harmless and nonpainful. Surgical removal is warranted if large, ugly, or bothersome.

When to Call Your Vet

Without a vet’s expertise or test results, it’s easy for our minds to get carried away and think the worst. Fewer than half of lumps and bumps you find on a dog are malignant. Still, they can look the same from the outside, so it’s hard to tell. Your veterinarian has many diagnostic techniques, including some non-invasive procedures like a biopsy and fine needle aspirate, that can determine what the skin mass really is.

2 vets and doberman

Your vet will often keep track of tumors for sudden changes. You can help keeping your pet’s medical records up to date so that you and your vet can compare how certain lumps and growths change over time. That way you’ll be sure to notice any sudden changes. Be sure to consult your vet if your dog has a lump that grows rapidly, oozes and doesn’t heal, or otherwise bothers you or your dog.

Meet the Author


Dr. Clayton Jones

Dr. Jones has 25 years of veterinary medical experience as a staff veterinarian and medical director of his own practice. He also is a member of the American Veterinary Medical Society and President of the US-Cuba Veterinary Cooperation Society.


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