A poor diet for your pets can be more damaging then you ever knew. Things like itching and dander could be related to poor nutrition. 
The first thing you need to do is to look for the basic ingredients that your food contains. Many dog foods are full of allergens, check the back of the bag for these ingredients-
Corn- dogs and cats cannot digest corn so it is a low quality filler in foods. Corn just passes through your animal without any added nutritional value.
By-Product- Some of these are harmful to your animals and are not a reliable source of protein. Some of the by-products can be horse remains, diseased livestock, feathers, feet, waste, euthanized animals, and roadkill. These can have high chemical traces and be tainted with bacteria and poison.
Peanut Hulls & Mill Run- This is the stuff off the floor at peanut plants. Like peanut shells.
Wheat and Wheat Gluten- An allergen similar to corn.
Look for these ingredients-
Whole meat (venison, turkey, bison or chicken) and you will know you are getting clean whole meat not left overs.
Fruits and Veggies- Fresh sweet potatoes, apples and berries add fiber and nutrients to the food.
Meal- These are dehyrdated “whole” products like turkey meal. They have calcium and are safer than by-products but are a little difficult to digest.
Oatmeal an Fish- Oats are great for animal tummies and are in premium foods. Flaxseed oil is great for your pets coat.