Many many years ago I put my cats on Hills Science diet c/d. This was due to 1 cat with bladder stones and then 4 others who had blockages (over a period of years). My vet had me put All the cats on c/d and never a problem again. An added benefit is they have the BEST coat every (very shiny and healthy). You must control the amount they eat thought, because they will get fat on it. Hills Science diet w/d will help with the bladder problem without the fat, (for an already overweight cat) but does not have the added benefit of the shiny coat. (I found this out when one of the cats was diagnosed with diabetes and needed to change foods). Ask your vet if he knows of this food, it may be just what you need. Good luck