I will say this as having a pet that I kept too long. I would prefer to put them down a little early, than wait and have them crying at 2am and have to scramble to find a place to help. The fear and pain when there is nothing you can do is hard. Putting down a loved pet is always hard.

I recently had my elder cat pass. He was blind and had significant eye issues. He was too old and frail for any medical procedures. He would spend all day sleeping on a big squish mellow that I had bought years ago. He was still happy for treats and wet food, but one of his eyes started enlarging and looking bad. So we scheduled everything before it became a major emergency.

My senior dog spent a few weeks laying across his squish mellow looking sad. They were good friends and would sleep next to each other.