My Yorkie has the same problem. Molly will let me brush her occasionally. If I don't keep her hair trimmed fairly short, she turns into a tangled mess. So, I've given up on having a long haired well brushed dog - she wears a puppy cut most of the time.

I worry about her being outside for long periods of time. I can't get her to wear a sweater outside even though it's cold in Iowa, she just doesn't stay out very long.