While I don't know if anything is ever tried and true with these things, I do know that 2 tbsp. of plain, low-fat yogurt twice a day have done a world of good in preventing these infections in mine. But I also know that some dogs are just prone to getting them. Good ear cleaning is a must, also. Make sure when you put the solution down in the ear that you pull your dog's ear toward his nose and then massage the ear to work the solution down into it, as this allows the cleaning solution to get further down into the ear canal. Good luck!