For my next project, one of the characters is an Alaskan husky-type dog. I spent today drawing doodles of husky dogs with a ballpoint pen. While drawing I watched The Dog Whisperer, a show about a "dog psychologist" who rehabilitates difficult dogs. There was a cute episode where he taught mail carriers how to interpret dog body language.
I think the most difficult part of drawing dogs is their mouths, because when their mouths are open they kind of look like they're smiling, and it's hard to draw that without it just looking humorous.