As cats age, they need a little help for their digestive systems, just like we do. While they won't eat soured dairy products such as yogurt, they still need the probiotics provided by them. Fortunately, there are several such products on the market that are specifically designed for our senior cats.
Vixen's favorite is Forti-Flora, made by Purina. I buy this from my vet's office. They report that all cats seem to love its flavor. That's true, as it's about the only supplement that Vixen will tolerate in her food. She's turned down joint support, hairball remedies, vitamins...pretty much anything else, no matter what flavoring is in it. But Forti-Flora seems to be like "kitty MSG" for her; she loves it!
More importantly, I've noticed that it's helped her digestion. She started taking it after a round of antibiotics for a kidney infection. I use about 1/3 of an envelope with each feeding of canned food, which at that time she was getting three times a day. When she'd finished the box, long after the antibiotic was done, I figured I could stop giving her the Forti-Flora. Wrong-o. Her diarrhea returned, with a vengeance. So now I give her 1/3 of an envelope each morning in her soft food. She still loves it, and it still helps her. So if your senior kitty is having trouble, perhaps this is a solution for you. If you've found others, please share them here!