My mutt Lloyd recently had an issue with a UTI that was really difficult to get rid of. He also had some stones, that went away when we got rid of the UTI. The vet said we should switch his food. I was looking at the Duck and Rabbit Instinct formulas. Even though it is kinda pricey for us, its still cheaper than the prescription food and Lloyd has always done better with grain free foods (he gets really itchy on foods with grains).