Pack Structure
Dogs are descended from wolves which have a very strict pack structure. The Alpha male and female get access to the best resources first and foremost. They dictate where the pack hunts, if any animal but they breed, and other social functions. You are the pack leader for your dog.
Most dogs want a leader. Some breeds even demand that you be a leader or they will become one. Dogs do not make good leaders, and we do not make good lower dogs. You would probably rather your dog not nip you because he decided it was time to play, or time to eat.
An easy way to avoid the entire ordeal of being a leader is to just enforce things that keep you a leader without too much work. Try implementing NILIF, or Nothing In Life Is Free. You control the resources of your dog, as as long as the dog remembers that there is no problem with who is in command.
Dogs interact with other dogs differently than they do with people. Dogs will almost always have their own pack order. The higher ranking dog will get toys first, demand attention first, go outside first, and generally get the best of everything. The lower dog should not be pampered in the higher ranking dogs presence, or a fight could ensue. This is very important in dogs who are serious about pack order.
Often people frustrate the dogs pack order by feeling sorry for the lower ranking one, and trying to make it up to them. Dogs do not live in an equal opportunity world, one will be high ranking, and one lower. You should be above both dogs at all times.
