Chihuahuas take their name from the Mexican state of Chihuahua, and the AKC registered its first one in 1904. They're easy to spot by the rounded, apple-shaped head, large upright ears and a smooth or long coat in nearly any color. The show standard caps weight at six pounds, but many pet Chihuahuas run a bit heavier.
Many Chihuahuas are bold, alert and closely attached to a favorite person, with a big-dog attitude. That confidence can turn into barking, wariness of strangers or snapping when handled roughly, though dogs vary a lot. Gentle socialization and early quiet training help, especially in close quarters. Chihuahuas are among the most common small dogs in shelters, so adults of many ages and personalities are often looking for homes.