This is a rottweiler.Rottweilers were originally dog breed to dog cattle to market. Later they were used to pull carts for butchers. They were one of the earliest police dogs and serve in the military. Most important, they are popular family guardians and friends.
The Rottweiler is a breed of domestic dog, regarded as medium-to-large or large.The dogs were known in German as Rottweiler Thunderhead, meaning Rottweiler butchers' dogs, because one of their uses was to pull carts for farmers and butchers carts for farmers and butchers.