Often likened behaviorally to terriers, the Chihuahua is a tiny but mighty breed that dates back to pre-Colombian times. Their range of colors and patterns match their capacity for training which tends to depend on the specific dog. Luckily, their charm and big-dog attitude are enough to please nearly any owner.

Intelligent, easy to train, and active, the Yorkshire Terrier is a spunky breed that's widely adored. Bred as pest control for factories and eventually becoming a favorite among the upper class, the loyal and loving Yorkie is the perfect size for apartments and loves curling up in its owner's lap. Yorkshire Terriers have a silky, hypoallergenic coat that sheds very little, making them ideal pets for people with allergies.