My dog actually had same problem, turned out it was from some food & type of shampoo & flea & heartworm med cause him itch like crazy. I now use human shampoo, cheap ones from dollar store, it actually help him scratch 95% lesser, and better skin & hair. and using different flea & heartworm med helped alot too. AND make sure all food has no corn or wheat, chicken (fat or flavor) added in them, that also cause my dog itch & develop rash.
If your dog goes out alot, try to rinse him/her off alittle a day, it helps "dirty" off the dog, also lead to lesser scratching |