Well, Yorkies are DEFINITELY NOT double coated dogs... just look and you can see that so I'm not sure where you heard that from, lol. In fact, they typically have thinner hair so they need extra "protection" in the cold seasons.
For me, I keep their hair really short. Zeus' hair is about 1-2 inchs. Thalia is about 3. They go for daily walks so it gets hot out. I don't keep them in long coats though.
__________________  Heather Zeus  | Thalia  |