The American Kennel Club standard for the Chihuahua breed is that they should be almost square in appearance, although the standard tolerates a slightly longer body for the female dog for the purpose of reproduction. The most important part of the American Kennel Club standard for the Chihuahua is that the skull be apple shaped with a tail that is carried very high and being of moderate length. The tail should ideally be curved in shape or at the very least form a semicircle with the tip pointing down to the loin region. Generally the Chihuahua will be greater in length than they are in height at the withers. Overall the Chihuahua is a compact dog that has a temperament of highly spirited intelligence while their behavior is neither snappy nor withdrawn. The Chihuahua should be small and dainty with an alert, quick, lively and very courageous behavior and temperament.
The Chihuahua standard set by the American Kennel Club states that the head should be well rounded with an overall “apple dome” shape. They should have lean cheeks and jaws with a muzzle that is moderately short, slightly pointed and has a definite stop. Eyes should be large and round, but not protruding. The eyes should be set well apart with the center of the eye being on a plane with the lowest point of the ear. While lighter eye color is permissible, the preferred color is dark or ruby. The ears should be at an angle of about forty-five degrees while being large and flaring. The scissor bite for the jaw should be regular and complete. And the upper teeth should closely overlap the lower teeth and be set square to the jaws. The jaw should be strong. The neck should have a slight arch and be of medium length.
When it comes to gait and movement the Chihuahua should have a stride that is springy, long, energetic and active while providing good reach and drive. The Chihuahua should have hind legs that move almost parallel to each other when viewed from the back, causing the foot prints of the hind feet to fit directly into those left by the front feet. Often when they increase speed the limbs will show a tendency to converge towards the center point of gravity or a single track. The dog should have free and springy movement while keeping their head raised and firm with no visible effort. For shorthaired dogs the coat should be glossy with a soft texture. For the longhaired Chihuahua the coat should be fine, silky and smooth or slightly wavy. All shades and color combinations are allowed by the standard. For a Chihuahua the ideal weight is between 1.5 and 3 kg. While lower weights are accepted, higher weights are disqualified.

The Chihuahua standard is very specific about placement of facial features and overall head shape. Quality Chihuahua information can provide you with the specifics of the standard.