Osteosarcoma in dogs

Osteosarcoma is a type of bone cancer. It usually affects one of the limbs. It’s most commonly diagnosed at around 7 years of age, and it appears more in large and giant breeds. 

Osteosarcoma is the most common malignant tumour of the bone. It’s a painful cancer and sadly, it has a poor outcome. Treatment aims to relieve your dog’s pain and improve their quality of life.



What is an osteosarcoma in dogs?

  • An osteosarcoma is an irregular growth of bone-producing and bone-breaking cells.
  • This cancer usually appears primarily in long bones in the front and hind legs. But can develop in the bones of the skull, spine, ribcage and others.
  • Rare cases arise in non-boney tissues like mammary glands (teats), liver and others.
  • This tumour is highly spreadable (metastases). 80 % of these dogs die due to lung metastasis.
  • The cause of this condition is unclear. There are very few tumours with a single known cause. Genetic and environmental factors (rapid growth, metallic implants, bone diseases) seem to play an important role.



What are the signs of osteosarcoma in dogs?

You might notice some or all of the following in your dog:

  • Limping
  • Swelling of the leg
  • Reluctance to climb, walk, or play
  • Tiredness
  • Reduced appetite
  • Losing weight
  • Changes in behaviour such as irritability or aggression

In osteosarcoma of the skull:

  • Difficulty eating
  • Eye changes such as a swollen eye
  • Nasal discharge
  • Face asymmetry



Are some dogs more at risk of osteosarcoma than others?

Although the direct cause is unknown, there are some risk factors to consider:

Size: Increasing weight and height are known risk factors, meaning that large and giant dogs are usually affected.


  • Boxer
  • Dobermann
  • Great Dane
  • Greyhound
  • Irish Wolfhound
  • Mastiff
  • Rottweiler
  • Saint Bernard
  • Scottish Deerhound
  • Still, any breed can be affected, regardless of size


  • Depending on the location of the disease the age predisposition can vary.
  • In long-bone osteosarcoma, this condition seems to be diagnosed more in middle to older age dogs (with an average of 7 years old).



How is an osteosarcoma diagnosed in dogs?

Diagnosis aims to not only investigate the primary tumour but also determine the extent of the cancer within the body or presence of metastasis. It includes:

  • A comprehensive history of your dog’s signs and any past bone injuries or surgeries.
  • A hands-on examination.
  • Radiographs (x-rays): very important tool, as a type of bone image can be highly suspicious of the disease. Your vet may also want to take x-rays of your dog’s lungs to look for any signs of disease spreading.
  • Blood and urine tests
  • FNA (fine needle aspiration test cytology): a small needle is used to collect a sample of the lump.
  • Biopsy: a bigger chunk of the lump is collected during surgery.
  • Advanced imaging, such as a CT scan may be necessary in some cases.


Vet treatment

What are the treatment options for a dog with osteosarcoma?

There is no cure for osteosarcoma, and sadly, the majority will not survive the disease.

However, treatment can improve your dog’s comfort and increase their survival time.

The treatment of choice for most dogs is a combination of surgical removal of the primary tumour (usually amputation) and chemotherapy.


Dogs adapt incredibly well after an amputation. Recovery is usually fast, within a few weeks.


Usually recommended after surgery to help control the spread of the disease.

The protocol can vary. The procedure involves injecting a drug into the blood every couple of weeks.

Dogs don’t have as many side effects from chemotherapy as humans. Occasionally, there is a temporary lack of appetite, nausea, tiredness and loose stools. These often last just a day or so after treatment.

Pain relief

Analgesic drugs: anti-inflammatories (NSAIDs), opioids, gabapentin, amantadine.

Bisphosphonates: their use will reduce bone pain and decrease bone destruction.

Radiation therapy: is another treatment option available. Although it’s not easily accessible and requires specific facilities and trained technicians.

Survival times

How long a dog with diagnosed osteosarcoma survives will depend on the location of the tumour as well as the extent of its spread.

  • Without treatment: ~2 months
  • Only with palliative care (radiation and chemotherapy): ~3-6 months
  • Amputation alone: ~6 months
  • Amputation and chemotherapy: ~1 year, in some cases 2 years


Home treatment

Caring for your dog with osteosarcoma at home

While most dogs have good mobility after amputation, your pet may need extra support. Consider:

  • Physiotherapy and rehabilitation
  • Complementary treatments such as acupuncture and massage

Because osteosarcoma is such a painful type of cancer, you may see that your dog’s behaviour changes, and sometimes they may even behave aggressively. Be mindful of these changes and take caution with visitors, children, and other pets.

When to consider euthanasia if your dog has osteosarcoma

Osteosarcomas in dogs often have a very poor outcome, and depending on the stage of the illness, your vet may discuss euthanasia as an option to prevent suffering. When making this very emotional and hard decision, there are some tools that can help you find the right moment to say goodbye by looking for consistent deterioration and poor quality of life.




Can osteosarcoma in dogs be prevented?

Sadly there is no known prevention for osteosarcoma.


When to worry

When to worry about your dog with osteosarcoma

Call your local vet if your dog shows any of these signs:

Call Joii if:

  • You need help assessing pain in your dog
  • You need help assessing your dog’s quality of life
  • Your dog needs help adapting after amputation
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