Large and giant breed dogs are most at risk for developing bone cancer, probably because their bones grow so rapidly.  It’s most common in middle aged to older dogs. The tumor usually forms on a limb causing a lot of pain and lameness.  Front legs are affected about twice as often as back legs.  Bone cancer spreads quickly, often to the lungs.  The sooner that you take your dog to the veterinarian, the better the chances that the treatment will be affective.  Veterinarians diagnose the cancer with X Rays and sometimes a bone biopsy.  Surgery, chemotherapy and radiation may be used to try to keep the cancer from spreading and to ease the dog’s pain. If your dog does develop any symptoms, don’t try to diagnose his problem by yourself and never give him any pet medication. Take him to your vet right away!