Osteosarcoma in a dog's front leg

A dog may favour one front leg, resist stairs or play, or react when the limb is handled. Swelling can develop around a lower limb joint or another section of the bone. Reduced appetite or a quieter manner may reflect pain, although these signs are not specific to cancer.

A front-leg bone can become fragile when disease changes its structure. A small jump or ordinary movement may then cause a fracture, which is an emergency.

Arrange a veterinary examination rather than exercising through persistent lameness. The veterinarian may assess gait, pain, joints, and the whole limb, then recommend radiographs and further imaging or sampling if a bone lesion is found.

Keep activity restricted on slippery floors and use a lead for toileting until advice is given. If a tumour is confirmed, options may include tumour removal surgery and chemotherapy, tailored to the dog's health and the lesion's location.

Seek same-day veterinary advice for sudden worsening lameness, marked swelling, crying when moving, or refusal to use the leg. Go urgently if the limb looks deformed or the dog cannot stand, because a fracture may have occurred.

What does the radiograph show? Could this be an injury or infection? Is the bone at risk of fracture? Is sampling safe and how should it be planned? What pain relief and activity limits are appropriate while results are pending?