Finding a lump on your dog can be worrying, but the good news is that most skin lumps in dogs are not cancerous. Dogs commonly develop lumps as they get older, and many are harmless changes, such as cysts or fatty growths. That said, every new lump should always be checked by your vet. Early assessment makes it much easier to rule out serious problems and, if treatment is needed, gives your dog the best possible outcome.
Skin lumps can develop for many reasons, including infections, reactions to bites or injections, benign growths and, less commonly, cancer. The right treatment depends entirely on what the lump is and where it is on your dog’s body.
The look, feel and location of a lump can give your vet useful clues, but appearances alone aren’t always reliable. For that reason, further testing is often recommended.
Your vet may suggest taking a small sample from the lump. This is most commonly done using a fine needle aspirate, where a tiny needle is used to collect cells from the lump. This can often be done during a normal consultation and usually doesn’t require an anaesthetic. In some cases, a biopsy is needed, where a larger piece of tissue is taken under sedation or anaesthetic and analysed to give a clearer diagnosis.
You should contact your vet every time you find a new lump, even if it looks small or harmless.
You should also seek advice if an existing lump:
Getting into the habit of checking your dog regularly can help you spot changes early and once a week is ideal.
Gently run your hands over your dog’s entire body, starting at the head and working back. Don’t forget the legs, tail, stomach and under the collar area. Be gentle around sensitive spots and remember that nipples are normal in both male and female dogs. Finishing with a treat can help make checks a positive experience.
If you find something new, take a photo and make a note of its size before contacting your vet.
If your vet advises keeping an eye on a lump rather than treating it straight away, regular monitoring is important. Taking photos, measuring the lump monthly and noting any changes in texture, colour or sensitivity can all be helpful.
If anything changes, arrange a recheck with your vet.
Not all lumps are the same, and many are completely benign (not harmful).
Some of the more common causes include:
These are painful, infected, swellings filled with pus, often caused by bites, wounds or stings. They tend to feel hot and tender and may make your dog feel generally unwell.
Lymph nodes are part of your dog’s immune system and can swell when the body is fighting infection. If you notice any of your dog’s lymph nodes are swollen, please have them checked by vet.
Cysts are round, fluid-filled lumps that form when a hair follicle or gland becomes blocked. Most are harmless, but they can become sore or infected. It’s best not to squeeze them, as this can cause inflammation.
Engorged ticks can look very similar to small lumps or skin tags. They should only be removed using a proper tick remover to avoid leaving parts behind.
These can cause short-lived swelling, redness and itching. Severe reactions are rare, but breathing difficulties, collapse or vomiting after a sting need urgent veterinary attention.
Small swellings can develop after vaccinations or injections. These usually resolve on their own but let your vet know if one lasts more than a couple of weeks or starts to grow.
These are blood-filled swellings, often caused by trauma. They can look bruised and may be painful, so veterinary advice is important.
Skin tags are common in middle-aged and older dogs and are usually harmless. Warts (papillomas) are more common in younger dogs and often disappear on their own over time.
Lipomas are very common, especially in older or overweight dogs. They are soft, slow-growing and non-cancerous. Many don’t need treatment, unless they become very large or interfere with movement.
These are benign lumps seen mainly in young dogs. They often appear suddenly and look red and raised but usually shrink and disappear on their own within weeks.
Some lumps are cancerous, including mast cell tumours, melanomas, soft tissue sarcomas and squamous cell carcinomas. These vary widely in appearance and behaviour, which is why testing is so important.
