The Shih Tzu is one of the many pure breeds recognized by the American Kennel Club (AKC), which is a revered organization where purebred dogs can register and compete. Shih Tzu dogs have many defining characteristics that will be listed later in this article. The important thing to know is that the AKC only allows dogs that meet breed standards and have a pedigree or documented lineage to compete in standard dog shows. Substandard dogs, even if they are purebred, cannot compete.

Though standard Shih Tzu have excelled in AKC competition, winning a record-breaking number of championships over the years, some Shih Tzu breeders selectively breed smaller members of the breed, which results in less-than-standard sized dogs. Miniature Shih Tzu, or Teacup Shih Tzu, retain the traits of the breed, however, are not recognized by the American Kennel Club. They can compete through alternative organizations such as the as the National Canine Association (NCA) and Chinese Imperial Dog Club of America.

The Shih Tzu breed has specific characteristics that separate it from other breeds. The American Kennel Club defines the breed standard and cites the range dogs must fall within to register and compete. Shih Tzu dogs must be sturdy with compact bodies covered in a double coat of long, silky fur in any color.

Later, they became the pets of Chinese emperors. Shih Tzu were recognized by the American Kennel Club in 1969 and have won a record-breaking number of AKC competitions since that time. Though Teacup Shih Tzu dogs are smaller than breed standard, they are still referred to as Chinese Imperial Dogs due to their illustrious history.

Shih Tzu descended from other Chinese dog breeds, most likely the Lhasa Apso and Pekingese, as much as 2,000 years ago. Shih Tzu means "lion dogs" and Shih Tzu were revered as holy dogs in China. Bred initially by Tibetan monks, Shih Tzu later became imperial dogs of various Chinese dynasties.

The Teacup Shih Tzu is referred to by many other names. Most often called the Chinese Imperial Dog (and registered as breed with the National Canine Association under this name), Teacup Shih Tzu are also called Toy or Toi Shih Tzu, Miniature Shih Tzu, Imperial Shih Tzu, and Pocket Puppies. Teacup Shih Tzu are smaller than standard Shih Tzu. They weigh only four to seven pounds as adults. Breeders use the smallest purebred Shih Tzu to create the tiny Teacups.

Like standard Shih Tzu, Teacup Shih Tzu dogs have long, silky fur in varying colors, dark, expressive eyes, and sturdy bodies. Teacups are usually bred to have shorter backs than the standard, to keep them from developing spinal disc problems. Teacup Shih Tzu may also have shorter snouts and a more doll-like face. They have the same happy, loving temperament as purebred standard Shih Tzu.

Teacup Shih Tzu are purebred just like standard Shih Tzu. They are not recognized by the American Kennel Club simply because they do not conform to the breed standard characteristics that are desirable in a Shih Tzu. Other organizations disagree and have registered the tiny Teacup Shih Tzu as the Chinese Imperial Dog.