Dr. Marie replied:

Hi and thanks for your question. There are a number of things in prescription renal diets (including Hill's k/d) that make them helpful to a cat's kidneys.

The reason why we want to restrict the protein level is because large protein molecules are harder for the kidney to process.

I often get people asking me if they can use "so and so food" from the pet store because the label says it has the same amount of protein as the prescription food. But, this doesn't tell us about the quality of the protein.

The prescription foods also have things in them to help reduce the phosphorus level. If phosphorus goes high in a cat with renal disease then the cat starts to really not feel well.

There is no need to worry that you are going to do harm by feeding a low protein diet. The people who make these diets know what they are doing and do indeed have the cat's best interest at heart. Of course, they want to sell more food, and the best way to do that is to help the cat live longer!

If your cat reaches a point where she was eating the special food and no longer is eating anymore, don't make the mistake of assuming that she doesn't like the food. Often, this can mean that the phosphorus level is starting to go up as well as the renal enzymes. If she is not eating then a trip back to the vet may be necessary.

I hope this helps!

Dr. Marie.

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