Our Fawn Boxer gave birth to 8 healthy puppies (5 girls 3 boys) who were seen by the vet on day 3 for a full examination and tail docking. At 6 weeks, mom began favoring the one female pup who looks just like her! I would give each pup time out of the whelping den and mom just let the others nurse or play with them for a little. This little girl, Gemma, would play rough with mom and she loved it and they played for an hour each time! At 8 weeks mom developed an aggressive behavior toward a brindle girl. If she was playing with a sibling mom would dominate her and make her submit. When we started taking the pups outside to play, mom and her favorite would play in a healthy manner and then mom would tackle the brindle and chase her under a chair where she would hide to get away from mom (she doesn't back down from her siblings only mom). I have never seen anything like this and would like to know if anyone has experienced this type of behavior? Mom is an incredible family dog with lots of patience with our grand children, the sire was very intelligent brindle male (maybe she is mad at him for giving her 8 puppys :) There were 3 brindles one flashy fawn who looked like her dad and two plain Brindle (dark). The one she picks on is a Plain Brindle. She wasn't too kind to the flashy girl either before she left for her new home. Any previous experience like this?