They can change a lot in a week, but I have never had one to gain that much more in that time frame, but BJH could be right about the scales, it sounds like she did switch them, and to let her go as early as she did should have been a dead give away, 8 weeks is way too young no matter what their size. I would have taken the puppy back if I had known you were not happy, but I wouldn't have switched them in the first place
