It may be you dog's food. If my golden eats anything with chicken or corn in it, her skin drys up & she starts to scratch. As long as we keep her to lamb, beef or rice, no scratching at all. You might want to change your food and see.
Lola (I like to post pictures):
My sisters lab has the same problem with corn meal in her food.That's were I got the idea to change Lola's food. My sister took her lab to the vet and it was the first thing recommended. Lots of dog food is based on corn or chicken meal. Have a look at the ingredients in your dog food. It might be the answer.
Paul