A livestock guardian dog (LGD) is a dog type bred for the purpose of protecting livestock from predators.
Livestock guardian dogs stay with the group of animals they protect as a full-time member of the flock or herd. Their ability to guard their herd is mainly instinctive, as the dog is bonded to the herd from an early age. Unlike herding dogs which control the movement of livestock, LGDs blend in with them, watching for intruders within the flock. The mere presence of a guardian dog is usually enough to ward off some predators, and LGDs confront predators by vocal intimidation, barking, and displaying very aggressive behavior. The dog may attack or fight with a predator if it cannot drive it away.