Osteosarcoma (bone cancer) in dogs


  • Osteosarcoma is a type of bone cancer.
  • Osteosarcomas are painful tumours that often first appear as hot, solid, tender swellings. They are most common in leg bones, but can affect any bone in the body.
  • Osteosarcomas are aggressive tumours that spread to other parts of the body (often the lungs).
  • Sadly, the outlook for a dog with an osteosarcoma is very poor.
  • Giant breed dogs are most at risk of developing an osteosarcoma.

What is an osteosarcoma?

Osteosarcomas are painful and aggressive bone cancers that spread quickly around the body. An osteosarcoma can develop in any bone, but they are most common in leg bones (see diagram below).

Osteosarcoma tumours destroy the bone around them, sometimes causing them to break (we call this a ‘pathological fracture’).

Osteosarcomas are most common in middle aged, large and giant breeds such as Irish Wolfhounds, Greyhounds and Rottweilers.

Illustration showing common places osteosarcomas develop

Common places osteosarcomas can develop. Click image to enlarge.


  • Limping (varies from mild to severe)
  • A painful, hot, hard swelling (usually on a leg)
  • An unexpected leg fracture
  • High temperature
  • Low energy (lethargy)
  • Lumps elsewhere on the body - occasionally, an osteosarcoma can develop in other bones or soft tissues.

When to contact your vet

Contact your vet for an appointment ASAP if you notice hot, hard swelling on your dog or if they are limping or seem to be in pain. You know your dog, if they don’t have the exact symptoms listed above but you are still concerned, it’s always best to contact your vet.


X-rays and sometimes bone samples are necessary to confirm an osteosarcoma diagnosis.

Treatment and outlook

Sadly, if your dog has an osteosarcoma, their outlook is very poor. Even with specialist surgery to remove an osteosarcoma, and chemotherapy to control spread, most dogs survive less than a year after diagnosis. This is because osteosarcomas are very painful and over 90% of dogs diagnosed have tumours elsewhere in their body (most so small they can’t be seen on scans). It’s important to consider this when deciding on a treatment plan. Treatment should be focused around pain relief and maintaining a good quality of life for your dog. Once your dog’s quality of life starts to drop and their tumour becomes painful, euthanasia is the kindest option. Every dog with an osteosarcoma is different and your dog’s treatment will be tailored to suit them as an individual. Your vet will discuss all your options and offer advice about when it is time to say goodbye.

Xrays showing healthy bone vs osteosarcoma

The osteosarcoma above has destroyed the bone and caused a fracture. Click image to enlarge.


Managing an osteosarcoma is often very expensive, especially if you opt for surgery and chemotherapy. It’s very important to speak openly to your vet about your finances, the cost of treatment, as well as what you think is right for your dog. There is often more than one treatment option, so if one doesn’t work for you and your pet, your vet may be able to offer another.

Prioritising dog insurance from the moment you bring your canine companion into your life is highly recommended. This proactive approach guarantees that you will have the vital financial support necessary to meet all your dog's healthcare needs.

Published: November 2019

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