He is so beautiful!!

Chocolatepuppy gave you the best advice. You'll know. When his quality of life starts deteriorating, and isn't doing what he so loved doing and not eating, that's a sign. If he's not in any pain, just make him as comfortable as possible. I have a friend who has a 17 year old cat who has termial cancer. She is stick thin and will oly eat turkey, ham or chicken baby food. The vet gave her 3 months to live, a year and a half ago!!

Try giving Odin some of that. He might enjoy it. You and Odin will be in my thoughts and prayers.