Buried one of mine out the back garden, dug down 5ft ( measured it )we were in the same boat with our dog four years ago, The vet to his credit was very honest , He said he could operate and it would be expensive and it might buy the poor dog 12 months maximum.
So we decided to put the doggy to sleep.
and put his toys etc down with him.
He was 18.
Chased every car that came into the park if it was strange lol.