Updated April 17, 2025 — Osteosarcoma in dogs often begins subtly with a limp, swelling on a leg, or even a sudden bone fracture, signs that can quickly lead to an emergency vet visit.
What Is Osteosarcoma in Dogs?
Osteosarcoma (OSA) is the most common primary bone tumor in dogs, with nearly 10,000 dogs diagnosed annually in the U.S. It accounts for about 85% of all malignant bone tumors in dogs and usually affects the limbs. This aggressive cancer is extremely painful, and without aggressive treatment, most dogs will not survive beyond one year.
Risk Factors for Canine Osteosarcoma
While any dog can develop osteosarcoma, the following risk factors increase susceptibility:
- Large and giant breeds: Great Dane, boxer, Rottweiler, Saint Bernard, Irish setter, Doberman pinscher, greyhound, German shepherd, Irish wolfhound, Leonberger
- Height and weight
- Older age
- Dogs with longer muzzles (dolichocephalic breeds)
- Lower risk in chondrodysplastic (short-legged) dogs
New genetic studies have shifted focus from individual breeds to breed groups, such as the mastiff-terrier group (boxers, golden retrievers, mastiffs), to assess risk.
Spay/neuter timing may also influence osteosarcoma development, though data is conflicting. The Golden Retriever Lifetime Study continues to monitor these variables.
Recognizing the Signs of Dog Bone Cancer
Common symptoms include:
- Limping or lameness
- Swelling or a growing lump on a limb
- Sudden fracture
How Osteosarcoma in Dogs Is Diagnosed
Veterinarians use X-rays to assess bone damage. Osteosarcoma typically does not cross joints, unlike infections, providing an important diagnostic clue. Still, a bone biopsy is often needed to confirm diagnosis.
Treatment Options for Osteosarcoma in Dogs
Amputation is the most common initial treatment and relieves severe pain. Most dogs adapt well, even with one less limb.
However, surgery alone offers a poor prognosis. Around 90% of dogs die within one year.
Additional treatments include:
- Limb-sparing surgery
- Radiation therapy
- Chemotherapy (some dogs live years post-treatment)
- New drug trials, such as losartan and toceranib combinations
- Immunotherapy, which uses the dog’s own immune system to fight cancer
Emerging Therapies and Research
Morris Animal Foundation is leading the charge with over 30 years of research into canine osteosarcoma. The latest funded studies include:
- Oral therapies combined with tumor vaccines
- Stereotactic radiotherapy with dendritic-cell vaccines
- New chemotherapy drug combinations
- Targeting the MYC gene as a biomarker and treatment target
Eight other ongoing studies explore everything from novel immunotherapies to advanced radiation methods.
How You Can Help Fight Osteosarcoma
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