I was in the EXACT position your in. With my dog, Rufus. He was really old, and had some really bad days, then, sometimes he seemed ok. It took a lot of thought, but we put him to sleep. I think you'll know when it's time, I just got this feeling that it was to much for him, and lots of other reasons..Anyway, you'll know it when/if it's Oreos time or not.