By Dial A Vet Veterinary Team
Dogs collect lumps and bumps as they age, and many are harmless. A Labrador with several soft fatty lumps, a young Boxer with a pink button on its ear, and a puppy with warts on its lips are all common sights in practice. But the same group of lumps also includes mast cell tumours and soft tissue sarcomas, which can look and feel very ordinary. Knowing the usual suspects helps you understand what your vet is thinking about, and why they will almost always want a sample rather than a guess.
Key takeaways
- Lipomas (fatty lumps) are the most common lumps in middle-aged and older dogs and are benign.
- Histiocytomas and warts are common in young dogs and often go away on their own.
- Mast cell tumours are the most common skin cancer in dogs and can look like almost anything.
- In eastern Australia, an embedded paralysis tick can be mistaken for a small lump.
- A fine needle aspirate is the simplest way to find out what a lump is.
Common benign lumps
Lipomas
Soft, smooth, moveable lumps of fat under the skin, often on the chest, belly and flanks. Overweight and older dogs, and breeds such as Labradors, are prone. Most simply sit there, but some grow large enough to interfere with walking. A rare type, the infiltrative lipoma, grows into muscle.
Sebaceous adenomas and cysts
Small, wart-like or cauliflower-shaped growths, often on the head, eyelids and legs of older dogs. They may bleed when brushed or become greasy. Cysts can feel like a firm pea and sometimes discharge a cheesy material.
Papillomas (warts)
Caused by a virus. Young dogs often get clusters on the lips, gums and around the mouth. They usually regress within a few months as immunity develops. Single warts in older dogs are often a different growth.
Histiocytomas
Pink, round, hairless buttons that appear quickly, commonly on the head, ears and legs of dogs under three. Many regress in one to three months, but they should still be sampled to confirm.
Abscesses
Warm, painful swellings full of pus, usually from a bite or a grass seed working its way under the skin. Common between the toes in Australian summer.
Injection site and insect sting reactions
Swelling after a vaccine, injection or sting. Most settle within days to weeks. Rapid facial swelling with hives is an allergic reaction and needs a vet the same day.
Lumps that can be cancer
Mast cell tumours
Can be soft or firm, raised or flat, and may swell and shrink, or redden after being handled. Boxers, Staffordshire Bull Terriers, Labradors, Pugs and Golden Retrievers are prone. Read more in our article on mast cell tumours in dogs.
Soft tissue sarcomas
Firm lumps under the skin, sometimes mistaken for lipomas. They grow slowly but send microscopic roots into surrounding tissue, so early, wide removal matters.
Mammary tumours
Lumps along the mammary chain in female dogs, especially those not desexed or desexed later in life. About half are malignant, so they always need checking.
Melanomas
Dark lumps. On the skin they are often benign, but melanomas in the mouth or on the toes are usually aggressive. See mouth cancer in dogs.
Swollen lymph nodes
Firm lumps under the jaw, in front of the shoulders or behind the knees, especially if several are swollen at once, can be a sign of infection or lymphoma.
The Australian lump that is not a lump
Along the east coast, paralysis ticks are often found by owners who think they have felt a small wart or skin tag, especially on the head, neck and front legs. Ticks have legs near the skin and a grey or blue-grey body. Remove a tick promptly and call your vet if your dog shows any change in bark, coughing, wobbliness or breathing. See tick paralysis in dogs.
When to see a vet
Same day: a bleeding or ulcerated lump, a hot painful swelling, a lump that is growing by the day, facial swelling, swelling with weakness or breathing changes, or a dog that is unwell.
Within a week: any new lump bigger than a pea, or a known lump that has changed.
Within a month: small, stable lumps not yet checked. If it is bigger than a pea and has been there a month, it should be sampled.
How vets tell lumps apart
- Fine needle aspirate: cells are drawn out with a thin needle and examined under a microscope. Quick and usually done without sedation.
- Biopsy: a piece of tissue is removed for a pathologist to examine when an aspirate is not conclusive.
- Staging tests: for cancers, X-rays, ultrasound or blood tests help check for spread.
Treatment ranges from monitoring to surgical removal, sometimes with further treatment by a specialist. If you have just found a lump, our step-by-step guide on what to do next can help.
FAQ
Can I tell a fatty lump from cancer by feel?
No. Mast cell tumours and sarcomas can feel just like lipomas. A sample is needed.
Should all lumps be removed?
Not always. Confirmed benign lumps can often be monitored. Your vet will weigh up the type, size, location and your dog's health.
Do lipomas turn into cancer?
Lipomas themselves rarely become cancerous, but new lumps can appear nearby, so each one should be checked.
How can I keep track of my dog's lumps?
Keep a simple map with measurements and photos, and update it every month or two.
Talk with a vet
If you have found a lump on your dog and would like help working out how quickly it needs to be seen, a Dial A Vet veterinarian can talk through your photos and observations. Chat with Dial A Vet. A bleeding, fast-growing or painful lump needs an in-person vet today.
References
- Merck Veterinary Manual: Tumors of the skin and soft tissues in dogs
- Veterinary Society of Surgical Oncology: See Something, Do Something campaign
- Vail DM, Thamm DH, Liptak JM. Withrow and MacEwen's Small Animal Clinical Oncology, 6th edition
- Miller WH, Griffin CE, Campbell KL. Muller and Kirk's Small Animal Dermatology, 7th edition
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. If you are worried about your pet right now, contact your local vet or nearest emergency animal hospital.