Skin lumps on dogs

Dog on white background


  • There are many types of skin lump that can develop on a dog.
  • Most lumps look similar from the outside, so it’s likely that your vet will need to take a sample of your dog’s lump to find out what it is.
  • Regularly check your dog for lumps and contact your vet if you find a new one.

General information

We know how worrying it can be to find a lump on your dog but it’s important to remember that there are several different types, many of which won’t cause problems or can be easily treated. Always have new lumps checked by your vet, even if they look harmless and especially if they have appeared quickly or are causing problems.

Types of lump

It is often impossible to tell what a lump is just by looking at it, there are many different types, including:

Abscesses - pus filled swellings caused by infection.

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

Haematomas - blood filled swellings, 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 and grow larger over time.

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

Benign tumours - despite being a type of tumour (a group of cells growing out of control), benign tumours are slow growing and don’t spread to the rest of the body. Benign tumours don’t usually cause problems unless they get in the way of other body parts, 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 a common in young dogs. They tend to be red, round and angry looking, come up very quickly, but then disappear after a few weeks.

Malignant tumours - malignant tumours are cancerous growths that often grow quickly and spread to other parts of the body. Common malignant skin lumps in dogs include:

  • Mast Cell Tumours - a skin tumour that often grows quickly and spreads to other parts of the body. Mast cell tumours vary in appearance and often grow and shrink in size.
  • Squamous Cell Carcinomas - a type of skin cancer most common on the ears, nose, mouth, toes, scrotum and anus.
  • Melanomas - a very dark (often black) skin lump common on the face, body, feet and scrotum.

Checking and monitoring

It’s a good idea to regularly check your dog for lumps. You might need to feel instead of look for them, especially if your dog has thick fur. If you find a lump or swelling, 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 lump should be checked, even if your dog already has some. This is because each new lump has the potential to be different from the last one.

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.

Illustration to show how to measure a dog's lumps

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

When to contact your vet

Contact your vet if you find a lump on your dog, even if it looks innocent or they already have other harmless lumps. Your vet may need to take a sample of your dog’s lump to find out what it is.

Consider insuring your dog as soon as you get them, before any signs of illness start. This will ensure you have all the support you need to care for them.

Published: August 2020

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

Illustrations by Samantha Elmhurst