Hi Mary, it's a difficult situation you are in since you are not the owner of the kitty. I do alot of cat-sitting and if I were in your shoes I would at least make sure she has a clean bill of health; that is, no kidney failure or heart troubles, etc. That way you can narrow it down to just age. The fact that she's not drinking much concerns me. Would she let you give her some water by mouth?

I looked after a really sweet orangie named Sandy and when he reached the age of 14 he really started to slow down and before he made the trip to the RB at 15 he was not eating much at all. He especially had a bad time during the heat of the summer. Good luck and please keep us posted.