My sincere condolences about your cat. I also had a cat with kidney disease, and the veterinary system was not very helpful about treatment. I had to learn most

My sincere condolences about your cat. I also had a cat with kidney disease, and the veterinary system was not very helpful about treatment. I had to learn most of it on my own. The "prescription" pet food situation is an example of free market entities subverting regulatory agencies. "Prescription" pet foods exist only through a selective lack of enforcement by the FDA. The manufacturers make claims that the food treats specific medical conditions. That's a drug claim. By law they would be required to test for efficacy and have it approved as a drug. But the FDA chooses to allow manufacturers to sell pet food that makes drug claims without testing or approval so long as they contract with veterinarians to only sell it under "prescription." It's not a prescription (it's not a drug!), it's a way to skirt regulation. For kidney disease you want foods high in moisture, moderate in protein and low in phosphorous. You can buy foods that meet these requirements at your pet food store. There are options that are much higher quality than said "prescription" foods hawked by Hills, Royal Canin and the like. They're just not advertised as treating kidney disease because they don't make inappropriate drug claims!