With their apple heads, big round eyes, large pointy ears, saucy expressions, and feisty dispositions, Chihuahuas are one of the most beloved breeds of toy dogs in the world. But these frisky little dogs aren't for everyone. Consummate lap dogs, they thrive on attention and constant contact with their owners, and are miserable when left alone. As pups they're extremely fragile, although they do outlive bigger breeds by many years. Housebreaking can...