Osteosarcoma
Osteosarcoma (OSA) is the most common type of bone cancer in dogs. It is a very aggressive form of cancer and is metastatic Meaning, that it will spread to other parts of the body. Typically, OSA occurs in large or giant breed dogs that are middle-aged to elderly. However, it is possible for any breed and any age of dog to develop this cancer.
Osteosarcoma starts deep inside the bone and grows outward destroying the healthy bone as it does so. As it grows, it gets increasingly painful to the dog causing lameness.
For more detailed information, please visit the following links:
Symptoms, Diagnosis and Treatment of Osteosarcoma