I can't offer any opinion on the hair...but Natural Balance (by
Dick Van Patten) has several dog foods without wheat, so assuming it's wheat gluten that's the problem that might help. My parents have their Westie on the vegan formulation because she has meat and wheat problems, but they also have several other formulations. They will send you samples and coupons if you send them an email.
The change in Sassy was amazing when they switched her to this food...prior to that she constantly had loose stool and scratched like mad.
Their website is
www.naturalbalanceinc.com and it contains contact information, as well as a description of all their products.
Good luck.