Looking at the Royal Canin SO, it says the purpose is to increase urine flow.
My dog had UTI’s, no crystals, and here is what I did: switched to all wet/moist food (4 or 5 star rated only, no white potato, I used to do all grain-free but he was gaining weight too easily) and bought him an electric circulating pet fountain (Cat Mate brand). He hasn’t had a UTI in almost 2 years, and none since I started that regimen. So try that if you want.
Also, Solid Gold makes a supplement called Berry Balance that is supposed to help with that, you add it to the food. When I called the company, they said not to use it in conjunction with prescription food. I assume that if you add it to food, it would create the same effect as prescription food but you’d be able to avoid the junky ingredients that are typical in vet food.
