I’m so sorry Mary that you are in the middle of that situation. First off…you are not stupid! I have been contacted in the past year from 2 different people who have been facing amputations of the front leg for their respective Great Danes. It is certainly something that is considered and done successfully in Danes. You are right in that a rear leg is an easier loss since they carry the majority of their weight on the front legs. All I can say about a vet saying that Danes don’t do well is that I would look for a new vet. Our vet said the best way to get rid of the pain, and bone cancer is very painful, is to get rid of the leg as fast as possible. She currently has a 14 year old, 3-legged Golden who had histiocytic sarcoma and is happy and living her best life that she can.
There are other considerations before amputation…if the cancer is already evident in the lungs then the dog probably won’t survive long. Or if the dog is overweight that would make adapting to 3-legs difficult as well.
Bottom line is that unfortunately he isn’t your dog. The owners sound set in their opinion on not giving him a chance. I’m not sure you can do anything to change that.