I have a male black labrador who is 9 years old. hes always had itchy issues since puppyhood but the last couple years it's been bad. hes been to 2 vets now and both say he has food allergies. the last visit gave me more insight he recommended a single protein single carb diet, duck or fish with potato. so I've been looking at limited ingredient dog food which is expensive, I can deal with that but I really dont want to waste any more. this isn't our first hunt for a dog food that will ease his itching and last time was a failing waste of money on food he didnt want to eat. so the question is what brand is best for food allergies?