We have 3 shepherds right now and have always had this breed although occasionally others at the same time. We train our dogs pretty rigorously and are very careful when we have visitors. Some folks do not understand when a dog has had enough or how to read their body language. The one with her teeth out is actually just playing with the puppy. They play like this all the time and she takes some pretty aggravating nagging and nipping from the puppy. All of our dogs get along very well and we plan to add one more, perhaps from a litter from the one with her teeth out. We are keeping them about 2 years apart in age so we don't lose them all at once. We once lost 4 in a single year ranging from 14 to 15 years old. The staggered ages also lets the older dogs train the younger ones which really speeds the training. They understand when its time to play and when they need to get in touch with their inner wolf. This is why I prefer this breed.