Tess had the same problem 1 and 1/2 year ago and the vet recommended Hill's s/d and she loved them. The problem was that so did Costello (they have more fat and taste better than the ordinary Hill's) but he was not supposed to eat them. Always a problem when one of several cats has to keep a diet. So it sounds good that you get a special product just for her, even if you have to force her.
Good Luck!
//Alice
Bookmarks