Like dogs? Not only do they make great companions, but they can make great protectors too. With defensive breeds like German Shepherds, Rottweilers, and others, protecting their own comes naturally. This makes them ideal for self-defense type training. Just make sure to start when they are young and to be consistent in their training so they are obedient and don't become too aggressive. Smaller dogs can be trained too; they just may not have the same protective instincts as other breeds and may take a little more work. Let's not forget the little dogs-- they may not be able to thwart an intruder with their size, but even the smallest dogs can be useful in alerting their families when someone is on the property that shouldn't be.