@farmerman,
She DOES have kidney problems...which I didn't know about (except theoretically, as at least the beginnings of such can be pretty much assumed in a 14 year old cat) until she became very sick with a chest infection recently and nearly died.
She is currently being managed for this problem, (with second generation ace inhibitors, thank you very much), to conserve her remaining healthy tissue, and special food.
I monitor her hydration very carefully, and other than eating like a little pig, then vomiting, she looks good.
She's actually been doing brilliantly and looking like a kitten again.
This unwellness has occurred a couple of days after each of the injections she has (I think to manage her lungs...I would have known at one point, but in the maelstrom of when she was so ill, I have forgotten exactly) from time to time.
She's vomiting her special food...which she has come to love, after a period of looking at me as though I am trying to kill her. It is a very unbecoming shade of yellow when regurgitated.
She has a very stylish Siamese figure......solid muscle...but with no real excess fat. So...she's healthily skinny....but, since she DOESN'T have much excess, I was a bit worried about not letting her eat today. Looking at it rationally, though, normally we DON'T eat when we feel nauseous...so I don't think 12 hours without food is going to kill her.
If she is still sick tomorrow, she'll go back to the vet.