Lexie's special food is dry only, she is not supposed to have anything else at all, she does drink plenty though,she does sneak the other cats food on occasion which worries me, they might leave a few biscuits and she is a real sneak , i cannot watch her 24/7, so far so good, been two years now, and her's are the struvite stones, yes you should find out from your vet which kind Irwin has, BTW what a beautiful boy he is indeed.