The Chihuahua is the world's smallest dog and is native to Mexico.  They are named for the state of Chihuahua in their homeland.  The origin of this breed is unknown; it was thought that they were descendants of an ancient, yet larger breed kept by the Aztec civilizations.  This breed was known as the Techichi, however, no archeological remains have been found to link the two.  Other theories believe that the dog was brought to Mexico by Spanish settlers, having the ancestors of the Chihuahua coming from China or even Egypt.

    Chihuahuas are of course best known for their small size, and to a lesser extent their large erect ears.  The coat of this breed can be both long or short coated hair.  Short-coated varieties can be either a very thin layer of hair or a thick coat.  Height normally ranges from six to nine inches at the withers, however some dogs will grow as long as fifteen inches.  Weight can range anywhere from two to six pounds, with some weighing in at as much as ten pounds.  Chihuahuas come in a wide range of colors, from solids to spotted, fawns, chocolates, silver, brindle, and merle, among others.
   
    The Chihuahua is a devoted and intelligent pet.  Their size makes them adaptable to many environments and is well suited for the city apartment life.  They do not, however, make good pets for children for these same reasons, their size and fragility.  Chihuahuas may become devoted to one person, making them jealous of other human and pet relationships.

    Sadly the Chihuahua is prone to various genetic diseases, including epilepsy, seizure, patella luxation, and hydrocephalus.  Care must be taken during birthing and also with their dental care.  Chihuahua also have moleras, a soft spot in their skulls, they are the only dog to be born with an incomplete skull, although it does fill with age.