Have you tried Hill's Prescription diet u/d? I know that it's not the most holistic food out there, but it worked for my Harley. He had both kinds, struvite and oxalate stones. We tried everything from making him homemade organic food to various holistic and prescription dog foods, as well as a specialty internist. During the time that we were "searching" Harley had to have 2 more surgeries, and ended up at emergency several times for severe bladder infections - it was frustrating because I felt like we were doing everything possible to prevent them from forming and it still happened! What finally ended up working for us is the prescription u/d and NOTHING else - no treats or any other food. We also got him a cysto every month to make sure that there were no crystals forming. I'm sure there's no universal cure - every dog is different, but it might be worth a shot
