TW: preparing for pet loss

I have a senior yorkie mix. He’s 15, and given his mixed lineage, it’s hard to know how long he’s likely to live. He’s definitely showing his age, but some times more than others.

When I rescued him, he had a gimpy leg from being hit by a car in his youth (he was four years old when I got him). He could still put some weight on it, but often runs with it lifted. The vet(s) have continued to confirm that the leg, while weaker than the rest, is fine, it just has muscle loss and a weak tendon but the blood flow is good and the bone healed fine. I mention this because he has arthritis, which has gotten a lot worse the last few years and sometimes it’s so bad I have to carry him outside to do his business and support his body while he relieves himself. Sometimes he needs a bath after.

Now, if this was the constant state of things, I would be heartbroken, but I’d put him down. The thing is, every time this has happened, it’s lasted for a few days and then he rallies. Most of the time he acts like a puppy and is excited and full of life and curiosity and is clearly enjoying his life. The vet says other than his arthritis there’s really no other explanation for this.

I’m not looking for medical advice. My question is more like… how long is it right to wait while he has one of his “episodes”? Even those few days I can hardly stand to see him so uncomfortable, but because he’s recovered multiple times, I always expect him to rally. But I know one day he won’t. So how long is too long to wait and see if he’ll get better?

Everyone wants their pet to go peacefully in their sleep, but I don’t want my little guy to suffer his way to the rainbow bridge, you know? I realize there’s no definite answer here I’m just looking for kind of a what would you do, here?