15. Chihuahua
The Chihuahua is a tiny dog breed named after the Mexican region of the same name. They often form a strong bond with one family member and can be fiercely protective, even when no real threat exists. Despite their small size, Chihuahuas are remarkably brave and rarely show fear. If they tremble, it’s usually a sign of being cold rather than anxious. While some believe they are difficult to train, this isn’t true—though shaping their behavior does require patience, dedication, and consistent effort. Highly intelligent, Chihuahuas respond best to steady, positive training, which helps them become well-mannered companions.