Fierce Loyalty Passive Increases maximum number of Zombie Dogs (and the amount summoned per cast) by +1. While the Witch Doctor has a Zombie Dog, Gargantuan, or Fetish alive, the Witch Doctor's movement speed is increased by 30%. The speed bonus is halved while in combat.
Establish dominance. They will obey.
Fierce Loyalty is a Witch Doctor passive skill, unlocked at level 45.