Rottweiler
Rottweilers can grow very large. They were first bred for their strength as they are used to pull small carts and herd livestock. Rottweilers are very courageous and loyal; thus, they have a tendency to act violently around strangers. Their strong personality can be controlled with proper training and it is fairly important to show strong leadership all the while. This is the reason why Rottweilers are perfect as guard and police dogs. While strong, they do love to play around. So much so that they sometimes mistake play for something real thus they have a propensity to go on full attack mode.
Image Credit: Pexels/Екатерина Мясоед