Cancer in dogs – signs and what to do

Updated 2026-09-30 · 1 sources

Based on: PDSA

Book a vet visit

Book a vet appointment if you think your dog has this – a vet needs to confirm it and plan the treatment. Cancer is a condition with many different types that can affect dogs.

What to do now

What you can do now

  1. Contact your vet.
  2. Note when it started, how often it happens and what else you see.
  3. Take a photo or short video to show the vet.
  4. Keep fresh water available.
  5. Let your dog rest somewhere calm.

Don't

  • Do not give any human medicine.
  • Do not wait if it gets worse.

What it is

There are many different types of cancer that can affect dogs, and some are more serious than others.[1] Not all cancers mean that a dog is going to die.[1]

Signs

  • A mass or lump
  • Low energy
  • Reduced appetite
  • Weight loss
  • Coughing
  • Drinking more
  • Vomiting or diarrhoea

How a vet finds out

  • Blood tests
  • X-rays
  • Ultrasound
  • Biopsy
  • CT scan
  • MRI

How vets treat it

  • Surgery
  • Anti-inflammatories
  • Fluids or a drip
  • Diet change
  • Chemotherapy
  • Radiotherapy
  • Medication
  • Pain relief

What the experts say

“Overview. There are many different types of cancer that can affect dogs, some more serious than others. It can be extremely worrying if your dog is diagnosed with cancer but it’s important to remember that not all cancers mean your dog is going to die.”

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

Get it on Google Play

OkPaw is on Android now – an iPhone version is on its way.

Common questions

What signs can cancer cause in dogs?

Signs can include a mass or lump, low energy, reduced appetite, weight loss, coughing, drinking more, vomiting or diarrhoea.[1]

How might a vet check a lump?

It is rare to be able to tell what a lump is just by looking at it, so a vet may need to run tests, including collecting cells from the lump.[1]

What affects the treatment a dog receives?

Treatment options depend on the type of cancer, whether it has spread and the dog's overall health.[1]

Sources

  1. PDSA

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages

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