I wonder if the dog just excitedly jumped up on the girl since so many dogs aren't taught to NOT jump and she fell and they got tangled up. That's a much more likely scenario. I had a kid like that at my first house when my kids were small. I was rocking my youngest at nap time (he was 2 and I just about had him asleep, grr) when the neighbor girl just walked into his room. On the second story. With the door shut. I was PISSED. I told her in no uncertain terms she is to KNOCK ON THE DOOR AND IF THERE'S NO ANSWER, YOU DON'T COME IN.
How is the dog? Do you know anything about temperament? Do you know who the breeder is?