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Found a lump on your dog?

Dog on white background


We know how worrying it can be to find a lump on your dog, cancer often jumps to mind. It’s important to remember that lumps aren’t always nasty; they can be benign (non-cancerous) or malignant (cancerous).

Always have new lumps checked by your vet and continue monitoring them for changes. If your dog has a lump (even if it is cancerous), there are often many treatment options available.


Many lumps, cancerous or not, look similar to the naked eye. Your vet might be able to tell a little bit based on how it looks, how quickly it’s growing and where it is on the body. To find out exactly what it is, your vet might decide to take a sample.

Benign lumps

  • Benign lumps are not cancerous. They are an overgrowth of cells.
  • They don’t spread around the body.
  • They can sometimes cause problems when they get in the way of other body parts (e.g. a big benign lump next to a leg might get in the way and cause pain when your dog is walking).

Malignant lumps

  • Malignant lumps are cancerous, they tend to spread around the body and grow more quickly than benign lumps.

You can read articles on the below to find out about specific types of lump.

  • Skin lumps
  • Mammary (breast tissue) tumours
  • Testicular tumours
  • Anal (bottom) tumours
  • Brain tumours and tumours in the spine
  • Tumours inside the abdomen (including spleen, liver, kidney, stomach, gut, ovary and womb tumours)
  • Tumours inside the chest (including heart tumours, lung tumours and thyroid tumours)
  • Bone tumours.

When to contact your vet

Contact your vet if you find a lump on your dog. Every new lump should be checked. If the lump isn’t removed, you will need to monitor it and have it checked again if it changes (i.e. if it grows, changes in how it feels, starts to bleed or become painful).

You know your dog best. If you are concerned about them it’s always best to contact your vet.

Do I need to have every new lump checked?

Every new lump should be checked, even if your dog already has lots of lumps. Each lump has the potential to be different from the last one.

Once your dog’s lump has been checked by a vet you should continue monitoring it.


Treatment varies depending on the type of lump and can include:


  • Some lumps don’t need treatment, just monitoring. Your dog should be checked at least once a year or more often if your vet decides.


  • Sometimes, surgery will be needed to take a sample from a lump or to remove it completely.
  • If the lump is in a place that makes it very tricky to remove your dog may need treatment at a specialist veterinary hospital.
  • In some cases surgery may not be the best option and medication may be recommended first.


  • Chemotherapy are a group of medications are used to try to get rid of a cancer, slow it down or send it into remission.
  • Dogs having chemotherapy need regular blood tests and check-ups to make sure they stay happy and without side effects during treatment.
  • In some cases, chemotherapy may be used to control symptoms only. This means that the aim is not to get rid of the cancer, but make your dog feel better for as long as possible.


  • Radiotherapy is a treatment which kills cancer cells with radiation. It is currently only available at a few specialist veterinary hospitals in the UK.

To remove or not?

Your vet may recommend removing a lump if it’s cancerous or benign and causing problems.

If a lump is slow growing, benign and causing no problems your vet may recommend leaving it where it is. Similarly, if the risks of surgery are very high or if your dog has an advanced cancer it may be more sensible to leave the lump alone.

Monitoring lumps

Keep an eye on:

  • Size
  • Texture (smooth or knobbly)
  • Consistency (hard or soft)
  • Pain
  • Discharge (bleeding or weeping).

Taking photographs and measuring the lump every couple of weeks will help you notice if it grows quickly or changes.

Illustration to show how to measure a dog's lumps

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

Checking testicles for lumps

If your dog hasn’t been castrated it is important to check for testicular tumours. Your vet can show you how to check your dog’s testicles. If you are uncomfortable checking them, book an appointment with your vet or vet nurse.

How will I know if there is a tumour inside my dog?

Lumps on the surface are easy to spot, but lumps inside are much more difficult. Annual vet check-ups will help catch problems early.

Tumours inside your dog can cause a range of symptoms, which is why it’s important to contact your vet if you notice any changes in your dog’s health.


Treatment for a poorly pet can become very expensive. Consider insuring your dog as soon as you get them, before any signs of illness. This will ensure you have the support you need to care for them.

It’s also very important to speak openly with your vet about finances and cost of treatment, as well as what you think is right for your dog. There are often lots of options and if one doesn’t work for you and your family then your vet may be able to offer another.

Published: September 2018

PetWise Pet Health Hub – brought to you thanks to support from players of People’s Postcode Lottery 

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

Illustrations by Samantha Elmhurst