Skin lumps on dogs


  • We know how worrying it can be to find a lump on your dog but it’s important to remember that not all lumps are cancerous.
  • To be safe, check your dog regularly and have any new lumps checked by your vet, even if they look harmless.
  • Most lumps look similar from the outside, so it’s likely that your vet will need to take a sample to find out what it is.
  • The treatment your dog needs will depend on what type of lump they have and where it is.

Types of skin lumps

Dogs can get many different types of skin lumps, including:

Abscesses - pus-filled swellings.

Cysts - fluid-filled pockets that often appear quickly, feel soft, and change size and shape over time. Cysts are usually harmless.

Haematomas - swellings filled with blood, usually caused by an injury or sometimes (much more rarely) a clotting problem.

Skin tags - soft, skin lumps that look similar to warts, usually attached to the body by a small stalk.

Warts - knobbly, uneven, pink/white coloured lumps that are often slow growing and have hair coming from them.

Non-cancerous tumours – non-cancerous/ benign tumours are slow growing and don’t spread to the rest of the body. They don’t usually cause problems unless they become very big, start getting in the way, cause irritation or become infected. The most common benign tumours in dogs include:

  • Lipomas - fatty skin lumps that often start very soft and become firmer as they grow. Lipomas are usually slow growing but can become very large.
  • Histiocytomas - histiocytomas are common in young dogs. They tend to be red, round, angry looking, appear very suddenly, and then disappear again after a few weeks.

Cancerous tumours – cancerous/malignant tumours often grow quickly and spread to other parts of the body. Common cancerous skin lumps in dogs include:

  • Mast Cell Tumours – these can appear anywhere on the body, vary in appearance and grow/shrink over time. Unfortunately, mast cell tumours often grow quickly and spread to other parts of the body.
  • Squamous Cell Carcinomas – these are common on the ears, nose, mouth, toes, scrotum and anus.
  • Melanomas – these are often very dark in colour (often black) and are common on the face, body, feet and scrotum.

How to check your dog for lumps

It’s a good idea to regularly feel your dog for lumps. If you find one, take a photo, make a note of how big it is (for example, compared to a coin) and get in contact with your vet. Every new lump should be checked because each one has the potential to be different from the last.

Do a nose-to-tail check:

  1. Start at their head and check their ears, eyes, and mouth
  2. Slowly and gently following the direction of their fur run your hands over their whole body
  3. Don’t forget to check their legs, tail, bottom, and genitals
  4. Be careful when feeling their mouth, tummy, and back end, as many dogs don’t like being touched in these places.
  5. Remember – nipples are normal in both female and male dogs, so don’t mistake these for lumps
  6. Once you’ve finished, give your dog a treat to make it an enjoyable experience!

If your vet has asked you to monitor a lump, take photographs and measure it every couple of weeks. It can also be helpful to make notes about the following:  

  • Its shape
  • Its texture (smooth or knobbly)
  • How hard/soft it is
  • Whether it’s causing pain or not
  • Whether it bleeds or weeps

If the lump changes, book a check-up appointment with your vet.

An illustration showing how to monitor your dog's lump

Measure your dog’s lump(s) every couple of weeks to keep a record

When to contact your vet

Always contact your vet if you find a new lump on your dog, even if it looks harmless.

Consider taking out dog insurance as soon as you bring your dog home, before any signs of illness start. This will give you peace of mind that you have some financial support if they ever become unwell.


The treatment your dog needs for their lump will depend on what type it is, and where it’s growing. Some can be left alone, but others need to be removed – speak to your vet for more information.

Published: January 2023

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Written by vets and vet nurses. This advice is for UK pets only. Illustrations by Samantha Elmhurst.