Shell, my Molly has had raised kidney levels for the past 4 years or so (I really need to check when I'm next at the vet). I tried to get her to eat the kidney food as well without any luck whatsoever; in fact most people on CatChat who have tried the kidney diet for their cats have reported a resounding failure
There are binders you can use - again most cats I know of won't touch food with them in it. She gets normal cat food; no senior stuff. With the other cats in the house there just isn't much point as I have very little control over who eats what. They are all grazers and happily move from bowl to bowl.
I have Molly on a daily dose of Fortekor and that is is... and with time the levels have all come down to within normal; albeit the higher side of normal. We probably should be doing repeat blood tests on her, but as the vet says - given her age (she's 20 and a bit now) there really isn't much point as neither the vet nor I am willing to subject Molly to countless procedures, pilling, prodding, poking, etc....
Maybe speak to your vet about Fortekor as well and if he's agreeable ask him for a quote how much it would be from him vs getting a prescription and then buying them online; it works out quite a bit cheaper than from a vet
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