If they were struvite crystals (what kind of crystals is very important, as food that makes one kind better can make the other kind worse), the Hill's C/D gets two paws up from Smudge, and you can get the canned in plain, chicken, or seafood flavor. He actually prefers the dry, but he likes the canned seafood flavor too. The first time I offered him some, he tore right into it.

Love, Columbine