Osteosarcoma

Osteosarcoma is the most common primary bone tumor in dogs, especially large and giant breeds, typically arising in the limbs near the knee, shoulder, or wrist. It is aggressive, causing destructive bone lysis, severe pain, and frequent lameness or pathologic fracture. Microscopic spread to the lungs is present in most dogs at diagnosis even when not yet visible. Treatment focuses on pain control and slowing metastasis.