Osteosarcoma cancer in dogs: what to know

A dog may favour a leg, tire quickly on walks, resist stairs, or react when a limb is touched. Swelling can appear over a bone, and pain may make a normally sociable dog withdrawn or irritable. Some dogs show reduced appetite or energy, but these signs are not specific to osteosarcoma. Sprains, arthritis, infection, and other bone problems can cause similar changes.

A veterinarian may examine the limb, take X-rays, and assess the chest or other areas when appropriate. Blood tests can support general assessment but do not identify the tumour alone. A tissue sample may be recommended when imaging cannot distinguish osteosarcoma from another bone condition.

Book a veterinary appointment for persistent lameness, swelling, or pain. Restrict running, jumping, and rough play until the limb has been assessed, and use a lead for short, controlled outings. Do not give human pain medicines unless a veterinarian specifically prescribes them; some are dangerous for dogs.

Ask the veterinary team to explain the purpose, likely benefit, and effects of each option. Depending on the findings, discussions may include surgery and medicines that act throughout the body. The oncology treatment pages on [Tumour Removal Surgery](/treatments/surgical-oncology/tumour-removal-surgery/) and [Chemotherapy](/treatments/systemic-therapy/chemotherapy/) describe these approaches in general terms.

Seek urgent veterinary help if your dog suddenly cannot bear weight, cries out, develops marked swelling, or has pain after a minor incident. A weakened bone can break with ordinary movement. Breathing difficulty, collapse, repeated vomiting, or severe distress also needs immediate attention. Keep the dog as still and supported as possible during transport.

What other conditions could explain these signs? Which images are needed? Would a biopsy change the treatment choice? How should activity and pain be managed at home? Should a veterinary oncologist or orthopaedic specialist be involved?