>Did the vet suggest food that would help prevent the
>crystals?
It depends on the PH of the urine. One type of crystals forms in urine that is too acid, another type forms in urine that is too alkaline (one is 'struvite" and the other is something like oxyate?). Two of my male cats have the exact opposite tendency, but a new Science Diet food called "CD" takes care of preventing both types of crystals.