Breed standards for this dog do not generally specify a height, only a weight and a description of their overall proportions. As a result, height varies more than within many other breeds. Generally, the height ranges between six and ten inches. However, some dogs grow as tall as 12 to 15 inches (30 to 38 cm). Both British and American breed standards state that a Chihuahua must not weigh more than six pounds for conformation. However, the British standard also states that a weight of two to four pounds is preferred and that if two dogs are equally good in type, the more diminutive one is preferred. The Fédération Cynologique Internationale (FCI) standard calls for dogs ideally between 1.5 and 3.0 kg (3.3 to 6.6 lbs.), although smaller ones are acceptable in the show ring.
Pet-quality Chihuahuas (that is, those bred or purchased as companions rather than show dogs) often range above these weights, even above ten pounds if they have large bone structures or are allowed to become overweight. This does not mean that they are not purebred Chihuahuas; they do not meet the requirements to enter a conformation show. Oversized Chihuahuas are seen in some of the best, and worst, bloodlines. Typically the breed standard for both the long and short coat chihuahua will be identical except for the description of the coat.
Chihuahua breeders often use terms like Teacup, Pocket Size, Tiny Toy, Miniature or Standard to describe puppies. These terms are not recognized by the breed standards and are considered marketing gimmicks to inflate the value of puppies. Chihuahua's are commonly referred to as either Apple heads or Deer heads, the former having short noses and rounded heads similar to that of an apple; the latter having longer noses and more elongated heads.
The Kennel Club in the United Kingdom and the American Kennel Club in the United States only recognize two varieties of Chihuahua: the long-coat, and the smooth-coat, also referred to as short-haired. They are genetically the same breed.
The term smooth-coat does not mean that the hair is necessarily smooth, as the hair can range from having a velvet touch to a whiskery feeling. Long-haired Chihuahuas are actually smoother to the touch, having soft, fine guard hairs and a downy undercoat, which gives them their fluffy appearance.
Unlike many long-haired breeds, long-haired Chihuahuas require no trimming and minimal grooming. Contrary to popular belief, the long-haired breed also typically sheds less than their short-haired counterparts. It may take up to two or more years before a full long-haired coat develops.
The Chihuahua’s history is puzzling and there are many theories surrounding the origin of the breed. Chihuahuas were used in the sacred rituals as they were considered holy in pre-Columbian Indian nations. They were also popular pets among the upper class. The breed draws its name from the Mexican state of Chihuahua, where the first of the breed were discovered.
Some historians believe that the Chihuahua came from the island of Malta in the Mediterranean. More evidence for this theory lies in European paintings of small dogs that resemble the Chihuahua. One of the most famous paintings is a fresco in the Sistine Chapel by Sandro Botticelli dated 1482.
The painting, Scenes from the Life of Moses, shows a woman holding two tiny dogs with round heads, large eyes, big ears, and other characteristics similar to the Chihuahua. The painting was finished ten years before Columbus returned from the New World. It would have been impossible for Botticelli to have seen a Mexican dog, yet he depicted an animal strikingly similar to a Chihuahua.
Both folklore and archeological finds show that the breed originated in Mexico. The most common theory and most likely is that Chihuahuas are descended from the Techichi, a companion dog favored by the Toltec civilization in Mexico.
Historical records indicate that the Techichi hunted in packs. They can only be traced as far back as the ninth century but it is highly likely that this is the Chihuahua's native Mexican ancestor. Evidence of this is that the remains of dogs closely resembling, but slightly larger than the average Chihuahua have been found in such places as the Great Pyramid of Cholula, which dates back to the 2nd century BC and predates the 16th century. There is also evidence to suggest that the Techichi may predate the Mayans.
The Toltecs were conquered by the Aztecs, who believed that the Techichi held mystical powers. In terms of size, the present day Chihuahua is much smaller than its ancestors, a change thought to be due to the introduction of miniaturized Chinese dogs, such as the Chinese crested dog, into South America by the Spanish.
A progenitor of the breed was reputedly found in 1850 in old ruins near Casas Grandes in the Mexican state of Chihuahua from which the breed gets its name. The state borders on Texas, Arizona and New Mexico in the United States, where Chihuahuas first rose to prominence and were further developed.
Since that time, the Chihuahua has remained consistently popular as a breed, particularly in America when the breed was first recognized by the American Kennel Club in 1904. Genetic tests place the Chihuahua with other modern breeds originating in the 1800s