It's better to ask this with nutritionist! If the food that he eats reflect to his health like dry skin or like thin coating as you said it's better to ask the expert! I'm not that expert but I have some experience about this before! About the coating and skin you can use virgin coconut oil, they are a lot of benefit that dog can get while using that product, and also I've learned that
exoticonlinepetstore published about the right food to give to our dog and it's very helpful for me.
Humans and dog are not the same that's why you need to be careful of what you feed to them because it will affect their health. But home made cook with the right ingredients and fresh ingredients is one of the best option for our baby. And the most important ingredients that we add to their food while prepare it is Tender Loving Care