Australian Cattle Dog
These fearless, energetic canines have boundless energy and you will tire long before they do. They can be overzealous which can lead to injury for you, for them or for others.
Australian cattle dogs are a hybrid of different breeds including the bull terrier, collie, dingo, black and tan kelpie, and Dalmatian. Their temperament is quite stubborn so they can be frustrating to train. Factor in their extreme energy and you are going to find an Australian cattle dog a real handful.