Boris is only four years old.  When he was very young, he started getting urinary infections with crystals and it seemed likely he might soon block (urethral obstruction). At that point, we developed a diet and herbal regime that has worked for him ever since. There is not one answer for these kitties but one thing is for sure, if you want an option to nasty commercial prescription diets, its a bit more work at first checking urine frequently, but holistic medicine can really help these cases.  PS: he is still cross-eyed, I couldn’t help that.