[PennysMum]

Unfortunately, k/d does have several of the most common food allergens in it-- and so do the Purina and Royal Canin kidney diets. I'm not sure what to suggest if you can't feed separately. :/

Maybe you could try speaking to your vet about some alternatives to the k/d? Some of the vegetarian diets out there have a fairly low protein level-- I think Natural Balance's vegetarian formula comes in at only 17% or 18%. That is still higher than k/d's protein level, but it is quite a bit lower than most of the dog foods on the market, and it might turn out not to trigger the other dog's allergies since it would at least knock chicken and corn out of the ingredient list.

Separate feeding would be your best bet, but it might be an alternative if your vet thinks that your other dog could stand the slightly higher protein level.