We have two cats, and sadly one of them has just been diagnosed with kidney disease, and so we've got to feed him a special renal diet.

Luckily, he seems to like the food - the problem is, so does his sister! We've ordered a pair of microchip bowls to try and stop her eating his food (and vice versa, though that's less common), but I'd like to know if there is a risk that she could come to any harm if/when she does manage to steal some of his when we're not looking?

We've also bought some of the 'normal' food from the same manufacturer for her, in the hope that she'll be satisfied by that.

  • Can you expand on what the special diet is? In many cases it is just healthier. Apr 9, 2019 at 17:51
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    @JamesJenkins we've got the Royal Canin 'renal' food for him.
    – Nick C
    Apr 9, 2019 at 18:01

1 Answer 1


Feeding cats in the same household different diets is a logistical nightmare (been there, done that!) so sympathies!

Royal Canin's stance is "only feed them to your pet if your vet has recommended them", now this doesn't mean that your healthy cat would automatically be in for harm if they ate the prescription diet, but there would likely be problems long term if this was the only food the healthy cat had access to.

The dietary adaptions for cats with Chronic Kidney Disease (CKD) primarily involve reducing protein intake (in order to reduce the load on the kidneys), however cats typically need quite a lot of protein in their diet (for lean muscle mass, coat, etc). specialized foods such as the Royal Canin Renal varieties try and mitigate the reduced protein levels by using protein sources that aren't too hard on the kidneys but still they ultimately have a significantly lower protein content then a "normal" complete cat food. (RC Renal has a ~23% protein content vs the 33-40% found in their non-renal care foods)

So if his sister steals the odd nibble at his "special" food it's not going to be a problem - as long as she is getting adequate protein through her own food. Him stealing some of her's is more likely to cause problems though.

  • Does this same data/analysis apply to dogs?
    – IT_User
    Apr 11, 2019 at 22:13
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    @bluerojo The context of the answer is purely cat - as per the question. The same may or may not be true of dogs but I couldn't say either way I'm afraid as dogs aren't really my area of knowledge. This could make quite a good separate question though? That way someone clued up on dog's diets may be able to provide the answer for you. Apr 12, 2019 at 14:45

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