Shoot. People used to place puppies and kittens at six weeks all the time. That was the norm. All the puppies and kittens we acquired when I was a kid were six weeks old when we got them and I don't remember any issues we ever had with them. Since they all died of old age, we had them for many years and if there was a problem, I would remember. We have a pyranees newfoundland dog cross right now. She is a great dog except for the fact her mother should never have been bred. She had a really good disposition but lousy conformation. Our dog is the same. Wonderful temperament but unsound hindquarters. Otherwise she is a nice dog.