Shoot, horse semen goes all over the globe. I spent two summer doing collections/processing/shipping several times a week with fresh cooled, dealt with frozen for my senior research project in college, and have seen lots of horses inseminated artificially with both frozen and fresh. While it is still required to do live coverings for Jockey Club, I'd be shocked if many were doing live with warmbloods. AI is sort of the norm at this point.
Now granted, I know far less about impregnating a dog, but unless it is 100x more complicated than with horses, I wouldn't think it would be all that difficult. I'd actually have guessed it was easier - don't dogs ovulate multiple times over a period of time? That was my understanding behind the multiple father litters. The tough part with frozen on a mare is that the frozen semen, once thawed, generally lives a fair bit less time than fresh cooled, so you have to make sure it is in there at the right time, rather than having the larger window fresh gives you.
That could be the most useless information ever if dogs don't get pregnant the way I think they do. Ah well. It is typed out.