Hello there. My name isXXXXX and I am sorry to hear about Princess but I am happy to hear she is improving already. That is a very good sign. Although FCE's can not be treated directly with medications your question about diet is very important! Besides a good quality diet for senior pets I strongly recommend starting her on Omega-3 fatty acids (fish oils). With her size she can have 1 capsule of over the counter fish oils that you or I would take twice daily. Start with 1 capsule a day for a week then go up to 1 capsule twice a day after the first week just to make sure the oil doesn't loosen her stool. The fish oil will do a lot for her cardiovascular system, joints, brain, kidneys, and skin. So it is a very good idea to have her on that. they do make products specifically for pets that you can buy at the pet stores. They are usually liquids that you put on their food and they work just as well so any of those will work. Also a good multi vitamin at her age designed for pets is also a great idea. Although her food should provide the majority of the vitamins and minerals the supplement will just make sure she is getting plenty. So most pet stored sell good quality multi vitamins that will work great for her. So good diet,fish oil, and multi vitamin. Again the fish oil is probably the most important. Also keeping her active is very important even as she is improving make sure she is getting good walks they will be shorter as she recovers but then increase them day to day as she improves. This will keep her joints and muscles in good shape and her cardiovascular system in good shape. I hope this helps and I hope this makes sense. Please let me know if you have any additional questions or concerns. I would be happy to help. Please do not forget to rate my response so I receive credit for my time. Thank you!