Osteosarcoma is one of the top 3 causes of death in Great Danes. It can appear very quickly as a swelling around the ankle area in the front legs. It is probably the most terrifying diagnosis a Great Dane owner can hear. Bone Cancer usually attacks dogs over 8, but it can start in dogs as young as 5 or 6, even occasionally 1 or 2 years old.
Diagnosis is usually x-rays and bone biopsy. Treatment is usually chemotherapy and amputation. Only 50% of the dogs that have the limb amputated live beyond a year.