Chihuahuas take their name from the Mexican state of Chihuahua, and the AKC registered its first one in 1904. They're toy dogs, usually 3 to 9 pounds, with an apple-shaped head, large upright ears and either a smooth or long coat in nearly any color. Shedding is low to moderate, so a weekly brush is usually enough.
Many Chihuahuas are bold, alert and strongly attached to one or two people. That confidence can come out as barking or wariness with strangers, so gentle socialization and reward-based training pay off. Chihuahuas are also among the most common small dogs in shelters, which means adults of many ages and personalities are often waiting for homes, and an adult's size and temperament are easier to read than a puppy's.