What is the most common bone tumor in dogs and cats?

• A. Osteosarcoma
• B. Chondrosarcoma
• C. Fibrosarcoma
• D. Ewing Sarcoma

Answer: (A)

Osteosarcoma is the most common primary bone tumor in dogs and cats. It originates from osteoblasts and classically affects the appendicular skeleton, especially the metaphyses of long bones, with large and giant breed dogs showing higher risk. This tumor is notorious for aggressive local invasion and rapid spread to the lungs, which is why comprehensive imaging and systemic therapy are central to management. Radiographically, you often see a mixed lytic and blastic lesion with aggressive periosteal reaction, sometimes described as a sunburst pattern or Codman triangle. Among the other bone tumors listed—chondrosarcoma (cartilaginous origin, often involving flat bones or pelvis), fibrosarcoma (fibrous tissue origin, variable sites), and Ewing sarcoma (rare in dogs and cats)—osteosarcoma remains by far the most frequently diagnosed bone tumor in these species, making it the best answer.