I have heard that people with allergies to dogs can use dandruff shampoo to keep the dander down with regard to allergies, I don't think it will hurt your dog, so use it, but don't get the "medicated" kind, just regular dandruff shampoo. I currently use an oatmeal kind of shampoo on my puppy, which says its gentle and contains a moisturizer.
For out Huskey/malamute we add a table spoon of extra virgin olive oil to their feed. We use the evo oil because it is pure olive oil not mixed with corn oil or veg oil. Both are not good for a dogs health or coat. The olive oil has the healthy cholesterol which will not clog their arteries. It's great for them and you will should see nice results in a couple of weeks. It's also great for you. I buy Arabic (mostly Lebanese) extra olive oil. It's cheaper cost and wonderful olive flavor makes it a favorite for chefs and nutritionist. You also need to not brush quite as often. Maybe every other day or every third day until this is resolved. And be gentle. Just because they are dogs does not mean they have tender delicate skin.
Hello country girl You should ask your vet, And different food you feed your dog May help with this problem. Also it would be advisable to Make sure your dog actually has dandruff , and not a skin issue-
If you have been washing your dog with human shampoo it can cause dandruff also my dog had dandruff because he was allergic to a type of shampoo. Also it could be caused if you wash your dog too much it can take away special oils that protect the skin and coat. With taking care of these problems you might want to switch your shampoo to oatmeal dog shampoo and only bathe them when ever they are dirty. So about once every two or three months.