My pup is scratching a bit as well. Adding oil to food is a good idea, which I may try if she keeps it up. (First, I want to switch brands of dry food.) The heat in the house must have a similar drying effect on dogs as it does people, after all.
I was think of switching to Wellbeloved, since it is the only "all natural" one in Pets at Home near me. It is so confusing. I literally read dog food labels for 30 minutes standing in the store yesterday and walked out with nothing. Except a new rubber squeeky toy, so I guess it worked out okay for Pets at Home anyway.

Stacey