Hi all, my old cat, 16 years old, just taken her to vet and she has ataxia, overactive thyroid, spindle cell tumor and borderline chronic kidney disease. I caught her falling down the stairs this morning as she is very weak on the right side of her body 
So difficult....vet says she will be alright for a while but may suddenly go downhill. My ds age 11 is upset as he loves her so much, she rubs his head, sleeps in his room, sits in front of him when he's on the computer and rubs his head although she won't be able to do this anymore as suddenly last night she lost full use of the right side of her body and cannot jump. Still eating using litter tray and washing herself but wagging tail and doesn't seem happy.
Sorry to talk about something so sad, just don't know if it's a good idea to delay the inevitable....we've had her since 1999 year old rescue cat 

Any advice welcome.