Wheat germ is something I'd go easy with. Wheat is a food item that very frequently causes allergy problems for dogs. The problem is that it's a gluten. Just because it's common doesn't mean that every dog will have a problem, of course. But I would still avoid giving it frequently (it's constant exposure that usually leads to allergies).
The value in wheat germ is that it is high in Vit E. So an alternative source of that vitamin would likely bring similar effects (it's always better via food than as a supplement). Other things good for the coats include flaxseed, fish oils, and eggs (in moderation, of course).