The Bark magazine did an article about this recently. I'd also suggest giving a small amount of coconut oil to your pup. It has so many health benefits. I buy mine from tropical traditions and get the gold label virgin organic oil. They have lots of sales.
Winterizing Your Dog's Coat | The Bark Coconutoil.com - Research on Coconut Oil's Health Benefits Coconut Oil - Certified Organic Gold Label Virgin Coconut Oil from Tropical Traditions