I'm so sorry to hear you lost your kitty. But glad that you posted this, although, I think most of us know about UTI.

It's true that if cats get food with a high quantity of Magnesium, Calcium and Phosphate, they are more likely to form crystals and block up. My cat Fister had struvite crystals also, and had a cahteter put in several times, before we finally decided to have him operated.

This, and kidney problems seem to be the most commom deceases cats get, and we should all try to prevent it by giving them the right food.