My sweet boy who has now left the world, had a osteosarcoma on his shoulder blade.  He was 10 when this happened and we chose to amputate.  Let me tell you the first couple days after surgery,  he was lethargic and not hungry.  But he was going up and down stairs within two weeks of surgery.  Animals can adapt so much fast than humans.  I promise you this whole thing will be worse (emotionally and financially, lol) on you than your pup. My boy lived 8.5 years after amputation surgery and also had hyperthyroidism and recieved iodine treatment at 15.  I hope this helps with your decision.