Oh man. I let Radar go to the bridge yesterday. Same issue, same place, same age.
I based my decision on him. He was a laid back boy. No fighting, no drama, just mellow. He did not tolerate pain well, and recovery from an amp would have been terrible for him. He was pleading with me to let him go yesterday.
It's hard to make this decision on a pup you haven't had for a long time. But, the others are right. You need to find out your options, then search your heart and look into his eyes and decide what the best course of action is. Many hugs to you as you make this agonizing decision. Know that whatever you decide, you're doing it with your heart in the right place.