Probably, the most common cause is either Dry Skin or Allergies. If you give him baths(ie... an inside dog) then it is probably dry skin as shampoo washes out all the natural oils in the skin. If it's an outside dog it still could be dry skin but another think to consider is allergies. Dogs can be allergic to certain things just like us humans. Sometimes something in their food or something in their environment. I agree with Bird, give the dog 25mg of Benadryl and see if that helps. Benedryl won't hurt him as it is one of the safest drugs you can take. (I know b/c i'm a retired MD).