Allergies (environmental and food), ringworm, and mites are other causing of itching in dogs.  Once dogs start itching they damage the skin and allow bacteria and yeast to invade.  Have your dog examined  by a veterinarian to determine the cause of the itching and start appropriate treatment.

 Try changing the dogs food. When looking for a good dog food you should look for the first five ingredients in the food. It should be more meat then corn. I found the perfect one for my dogs Exclusive. Also 3 of my dogs have very dry skin. Try to find a conditioner with solfadene in it or you can try using moisturizing conditioner. So far when I give them a bath I wash them with flea shampoo then give them a real thick coat of conditioner work it in then let it sit on them for about three-five minutes rinse it off and they are good until the fleas come back or they get dirty from playing outside