He's the grey.

Yes, he's just getting old. He's seventeen years old, and is really starting to fail. He's been having violent seizures for months now (a holdover from a kittenhood poisoning that damaged his nervous system) and now he's starting to have trouble standing. He's nothing but a sack of bones and skin. Not only that, but he's having trouble going to the bathroom (he won't use the litterbox anymore, and will occasionally lose control in other places.)

I can tell he's in pain, and he's had a great run on life. I just don't want him to hurt anymore.

He's been an amazing cat. He deserves the best.