This article is from the Chihuahua Breed FAQ, by firstname.lastname@example.org (Melinda 'Bob' Casino) with numerous contributions by others.
Chihuahuas go under the classification of "toy breeds." The Chihuahua
can be short-haired or long haired. The breed standard, approved
September 11, 1990 disqualifies any dog over 6 pounds from the
conformation ring; however, they can weigh up to 9 pounds or more.
One of the Chihuahua's most distinctive characteristics is its head,
which is well-rounded and referred to by breeders as an "apple-dome"
type skull. In contrast, its muzzle is extraordinarily tiny in
contrast. Pink noses are sometimes found on blonde Chihuahuas.
Another distinctive physical feature of the Chihuahua is the ears:
large, held erect, and flaring to the sides at an angle of about 45
degrees, the Chihuahua uses its ears to express a variety of emotions
The eyes, usually dark and luminous, are wide-set. Again, blondes may
have lighter eyes. Tears are often produced in abundance to keep the
large eyes lubricated, and it is not unusual for tears to fly from a
Chihuahua's face when it shakes its head during play.
The back should be level and the rib-cage rounded. Some Chihuahuas
may actually have barrel-shaped rib-cages, but professional breeders
find this undesireable. The hindquarters are muscular and thin.
The Chihuahua has stick-like legs and dainty feet. The tail is
longish carried either in a sickle fashion or in a loop with the tip
touching the back.
Finally, coat color: there are a variety of shades, including
brindle, blonde, black, brown, fawn, blue, and "splashed." It is
interesting to note that Mexico prefers the jet black with tan
markings, and the black and white spotted; the United States
overwhelmingly prefers the solid colors, especially fawn.