Does your vet want her on a special diet because of her kidney issues? If so, I'd look into homecooking for her. We have a list of canine nutritionists in the YT library:
http://www.yorkietalk.com/forums/yor...itionists.html
Lady will be sixteen later this year and I have been cooking for her for about three years now. She has multiple health issues plus she was starting to get picky about her food and lost weight. Homecooking has made a huge difference in her appetite and health.