Originally Posted by
BeerAndPoker
He will be putting strain on his other legs, especially the other back foot which likely weakens it over time.
At his age vets are uncomfortable doing some procedures because it could backfire making it worse and they probably fear being sued. If they are actually an honest place they might think the time he has left might not financially be worth it for most customers (you don't fit in that category obv) because the dog on average could live another year or two (he could live months or 6 more years who knows).
My advice is to get a second opinion and let them know money isn't an issue not that you want them to screw you but it's about what will be best for your dog for the rest of it's life.
Many situations with a pet can be different tho.
When I was young I had a puppy who was very hyper. One morning getting ready for school it escaped outside and someone was chasing it then it ran into the road getting hit by a car. It was very sad! The puppy could have lived with two good legs, one gimpy one, and another one gone.
Since we were attached but not to the point of years of having her we decided to put her down because she wouldn't live a good life being this young, very hyper puppy wanting to play who couldn't. At the time I remember being very depressed having to do this as a 10-11 year old but looking back in my particular situation, which is way different then yours it was the right choice.
Best of luck with what you decide to do but maybe the second vet opinion would be worth considering.