Shadow had two serious urinary tract infections before he was prescribed the Purina UR formula cat food. We tried over the counter urinary tract formula, but he got the second infection anyway. He has been free of problems for several years now since eating this food. My neighbor's cat was started on this food after his first bout with urinary tract problems and has also been free of problems ever since. It is an expensive product, but well worth it both in comfort for the cats and lower vet bills for the humans.