Chihuahuas are very small dogs, and are the smallest breed recognized by some kennel clubs.[9] There are two main varieties recognized by kennel clubs, the short-haired and the long-haired.[9] There is a second varietal split as well, having to do with the shape and size of the dog's head. These two descriptive classifications are "apple head" and "deer head", but only the apple head is conformationally correct.[10]
Temperament
The temperament of its human guardian can make a difference in the temperament of the pup. Tempered Chihuahuas can be easily provoked to attack, and are therefore generally unsuitable for homes with small children.[18] The breed tends to be fiercely loyal to one particular guardian and in some cases may become over protective of the person, especially around other people or animals. If properly managed by older children, 13 and up, they can adapt to this kind of living with a dedicated guardian. They do not always get along with other breeds,[18] and tend to have a "clannish" nature, often preferring the companionship of other Chihuahuas or Chihuahua mixes over other dogs.[19] These traits generally make them unsuitable for households with children who are not patient and calm.[15] Chihuahuas love their dens and will often burrow themselves in pillows, clothes hampers, and blankets. They are often found under the covers or at the bottom of the bed, deep in the dark and safety of what they perceive as their den.