with the surgery.

The risk of the surgery is that the dog would never awaken. If it doesn't awaken, is that any different than putting it to sleep?

In general the danger of anesthesia in an older dog is the way the liver metabolizes the drug(s) used for anesthetic. Most Vets will insist on a liver panel profile before surgery, and can often adjust the types of drugs used and dosage to fit the individual dog. This is not to imply there is no risk, but the risk can be minimized.

The bottom line is that the decision to put your dog to sleep or not is your decision. No one can make it for you. In general if the dog seems to be content and happy, you should consider continuing its life. But again it's your decision.

It's curious you indicate that nothing has helped with the arthritic pain. Is is assumed your have tried the usual NSAID drugs such as Deramaxx, and Metacam. If no relief has been obtained you might ask your Vet for low dose Torbutrol given once every other day.