How do dogs determine the leader in their pack?
In the wild, dogs or wolves live in packs and have a very defined social structure. Domestic dogs also do well in groups when the canine social structure is established. Order is maintained within the group when each dog adheres to the dominance hierarchy. There is always only one alpha dog, or pack leader, and the rest fall in line. If another dog challenges the hierarchy, there will be unrest and fighting within the pack.
Dogs can either be dominant or subordinate. Our modern-day dog packs normally consist of one or more dogs and family members. This relationship inside the home is different than how dogs behave in the wild, but the hierarchy still exists. A healthy relationship at home will have one of the family members as the pack leader, with the rest of the family members and the dog or dogs following the pack leader.
Within a group of dogs, a pack leader is normally established very quickly. A dog with a dominant-aggressive personality will try to show his or her place among the group by acting somewhat like a bully. If any other dogs try to challenge this dog, he may react aggressively to defend his position as the pack leader. There is also normally a beta dog, who is also a dominant dog, but does not show the leadership or aggression as readily as the alpha dog.