Chihuahua

The saying size doesn’t matter typically holds in the case of Chihuahua, as its attitude is no less than a big dog’s. Though this breed weighs no more than six pounds, they are excellent watchdogs thanks to their conservative nature. In fact, out of all the little canines, Chihuahuas are perhaps the fiercest.

So if they are left untrained, their unruly behavior will get you on your knees. Moreover, Chihuahuas are dubbed as the little Napoleon if not appropriately disciplined. Though they are loyal towards their masters, given their size, these canines can quickly feel threatened around larger pets and playful children.