We have a dane that we had to switch to a completely raw diet to avoid the problems with the digestive track. He went 9 months without anything close to solid mostly liquid due to allergies. Our vet was a skeptic to until she realized how much better he was looking and feeling after switching. The acne around his mouth is completely gone as well.
I have come to realize that vets are not nutritionists and know very little about foods and it is left up to us owners to educate ourselves.