I was also going to add that cats with urinary problems need more moisture in their diet. My RB Storm became blocked 2 times so he needed the PU Surgery but he still needed to eat a lot of canned food for added moisture. He was on Royal Canin's Urinary S/O diet in both dry and canned for a while but he still wasn't doing too well because he'd still have some UTI's. It wasn't until I changed vets and started him on a grain free diet of both dry and canned food that he never had any more problems again. I started out feeding everyone Innova Evo because my RB cat Starr had IBD/Colitis but this food actually helped all of my cats improve their health. The fat ones lost weight and they all had much more energy. They were also very satisfied will the 4 small feedings that I fed them. I think that most of the veterniary RX foods have horrible ingredients in them and they cost a fortune. Most vets aren't taught much about nutrition so they only know about the veterinary RX diets that their clinic/hospital sells. Both my regular vet and my holistic vet at the time approved a grain free diet for my RB Storm. They just told me to be sure to feed him plenty of canned food too. I no longer feed my cats Innova Evo since it was bought out by Proctor & Gamble but they're still on a grain free diet and doing well. There are many more grain free options out there now and many grain free canned foods as well. I'd do some research about this if I was you. I'm sure that you could also get the sodium content of certain foods by calling the companies too.