The Official AKC Breed Standard describes the Chihuahua as a small dog
that comes in two varieties or coat types. The difference in coat type (the
Long Coat and the Smooth Coat) is the only official description used to
identify a difference within this breed.

For the purpose of showing and record keeping, the American Kennel club
includes the Chihuahua (along with 19 other breeds) in the Toy Group.
Therefore, irrespective of their weight or physical stature ALL Chihuahuas
registered with the AKC are considered to be a toy breed of dog.
As with all living things, there will be size variance between individual
dogs within this breed. Look within the human family - brothers and
sisters will differ in height and in weight, as well as other physical
attributes. They are described as humans, male or female, and there is
seldom if ever a need to break the description down further. The same
holds true in regard to the Chihuahua; they are
Chihuahuas - Long Coat / Smooth Coat!
Unfortunately, the additional adjectives used to describe the size
differences and physical appearances are many and have been misused for
so long they now seem legitimate. Teacup, Pocket Size, Tiny Toy,
Miniature or Standard - are just a few of the many tags and labels that have
been attached to this breed over the years. We are concerned that these
terms may be used to entice prospective buyers into thinking that puppies
described in this way are of greater monetary value. They are not and the
use of these terms is incorrect and misleading.
Occasionally, within a litter, there may be a puppy that is unusually small.
That puppy is a small Chihuahua and any other breakdown in description
is not correct. To attach any of these additional labels to a particular
puppy is to misrepresent that Chihuahua as something that is rare or
exceptional and causes a great deal of confusion among those pet parents
to be who are looking for a Chihuahua.
We would caution the perspective puppy buyer not to be misled by these
terms or names for a small Chihuahua.
We recognize that many Chihuahua lovers do want the very small puppy.
While they are adorable and can be perfectly healthy, the buyer should be
cautioned as to the extra care that may be required with regard to their
general health and well-being.
This is a Teacup                 and            This is a Chihuahua