Just wanted to say, try switching to a food with alternative ingredients and see if the itching stops. This needs to be done for at least a month or more, after slowly switching. The most common allergies for dogs are beef and dairy followed by chicken and corn. Those ingredients are in most dog foods. My dog was switched to Eagle Pack fish and oatmeal based kibble, and he is much better now, barely scratches and his coat is soft and shiny.
Prevent a litter
Fix your critter