Within every wolf pack are two leaders and a group of subordinates. The leaders, called the alpha pair, are clear reminders of their power. They do this through their body language.
One way a dog shows dominance is by making itself look bigger. It lifts its head high and thrusts out its chest. When a dog meet a stranger, the hair on its back and shoulders might rise. This,too,makes the dog appear larger. The message it clear: I am bigger than you , and I'm in charge.