My almost-19-year-old male kitty, Gus, has been diagnosed with
FIP. (Sorry, couldn't make the link work. [mod: fixed for you]) He's got the effusive version, which means his abdomen fills with fluid. I took him last weekend and had the fluid aspirated, but he's filling up again and I don't plan to put him through that any more. The vet and I agreed that I'll keep him here until the fluid starts to impact his comfort level and breathing, then it will be time to let him go.
And, you know, I'm not putting this in Vent and Rant because I know how lucky I've been to have him healthy for so long. We're having some quality cuddle time this week, and I hope to be able to let him go with dignity and before he gets too uncomfortable. He is, and has always been, a Very Good Cat.