Biology, diagnosis and treatment of canine appendicular osteosarcoma: similarities and differences with human osteosarcoma.

Osteosarcoma (OSA) is the most common primary bone tumour in dogs. The appendicular locations are most frequently involved and large to giant breed dogs are commonly affected, with a median age of 7-8 years. OSA is a locally invasive neoplasm with a high rate of metastasis, mostly to the lungs. Due to similarities in biology and treatment of OSA in dogs and humans, canine OSA represents a valid and important tumour model. Differences between canine and human OSAs include the age of occurrence (OSA is most commonly an adolescent disease in humans), localisation (the stifle is the most common site of localisation in humans) and limited use of neoadjuvant chemotherapy in canine OSA.