cat wont eat science diet C/D

Question
I have two male cats, both 3 years old.  I had been feeding them Purina ProPlan wet and dry food until Christmas when one cat was hospitalized for 6 days due to a nasty UTI and kidney stone.  He is now on mix of hills science diet C/D wet and dry food for the rest of his nine lives to prevent the formation of any struvite crystals.
I attempted to slowly ween the other male onto the C/D food from the ProPlan to hopefully prevent any potential urinary tract issues. When we finally gave him 100% C/D (mix of wet and dry), he refused to eat.  After 24 hours, I gave in and gave him ProPlan specialized for urinary tract health.  
I have read quite a few responses on "Ask the Veterinarian" and there seems to be a consensus that Purina is not highly recommended, which our vet also agrees with. C/D is such a good food, and there isn't an over-the-counter food with the same low pH level.
I am stuck.  I don't want to face another sick cat in the future if UTI's are so common in male cats, and frankly can't afford another $3K bill.  Do you have any recommendations?

Answer
Hi Erin,
I need some clarification on you saying he refuses to eat. In my experience with C/D, cats are very satiated with it after eating it for a week or so and will not appear very hungry. They will nibble on it here and there but will not eat it like they do less nutritious foods.

C/D is packed with fat and nutrients so that it takes very little food to satisfy a cats energy needs. You said that he was eating up until he had the 100% C/D. I wouldn't give in and give him the other food, that just makes him a picky eater. I would go back to the C/D alone and just watch him. I have never seen a cat refuse it- but it might take a few days. He is probably nibbling on the sly- don't confuse that with not eating. That is how a cat on C/D eats. I had three of them on it once and they rarely ate- but they were all healthy and shiny! So they were getting what they needed.

You could try some of the canned mixed into it also, that helps to entice a reluctant cat.
Some pour a small amount of tuna water or chicken broth on the food as well to get them started.

But don't give up and don't give in. Purina foods are not what they are made up to be- on the inside they are still made with dock-side ingredients and cannot be trusted nor do they have the optimal nutrition that Hill's foods have.

If the one cat will absolutely NOT eat this food, then as you vet to recommend one of the Science Diet formulas for him. Even if the other cat gets into it, it won't harm him that way. But you will have the hassle of feeding two separate foods.

So take away the Purina and leave out the Hills. Only 1/4 to 1/2 cup a day of this food is all they need in their bowls. You might want to measure it out to prevent obesity and to gauge how much they each are eating.

Let me know if you have any more questions. You might want to look into getting some pet insurance as well.....