My lovely lady is aged 17. She became increasingly wobbly over the last fortnight, and the vet says it is spinal arthritis. He also did various tests, and her kidneys are not what they were.
He gave her a cortisone injection and she seems happier, we are going back to vet next week. He said she was v v likely to have been in pain, I feel awful as she has been yowling but I thought she was just getting more imperious in her old age 
I am wondering about the likely course of things for her (and me).
Vet says to feed her Whiskas Senior and fish.
She is asleep in the garden. She has been such a comfort throughout her whole life even when she brought home live presents, I owe her a lot...