The Shih Tzu and Imperial Shih Tzu (in English pronounced /ʃiːt zuː/, in singular and plural) (獅子狗 pinyin: Shīzi Gǒu, Wade-Giles: Shih-tzu Kou) is a dog breed which originated in China. The spelling "Shih Tzu", most commonly used for the breed, is according to the Wade-Giles system of romanization. The Shih Tzu is reported to be the oldest and smallest of the Tibetan holy dogs, its vaguely lion-like look being associated with the Snow lion. It is now often called by a homonymic name, "xi shi quan" (西施犬), based on the name of Xi Shi, regarded as the most beautiful woman of ancient China. The Shih Tzu and The Imperial Shih Tzu is known to be a companion dog with great charm.
The Shih Tzu has been around for a long time. The Shih Tzu was bred to sit around the palace of the Emperor of China and bark when people or animals approached: this is allegedly to alert people to the presence of unwanted visitors. It is believed that this ornamental breed was created by breeding the Bei-jing gou (Pekingese) with a Tibetan dog breed, the Lhasa Apso. Recent DNA analysis confirms that this is one of the oldest breeds of dog. The Shih Tzu is also known as the Chinese/Tibetan Lion Dog or the Chrysanthemum Dog. It is called the chrysanthemum dog because its face looks very much like the flower. In 1994, the Shih Tzu became the 12th most popular breed of dog in the AKC's 139 breeds with more than 37,000 new individuals. 
There are differences between the American and European Shih Tzu standards. The FCI standard is used in Europe and the AKC standard is used in the United States.
The Imperial Shih Tzu or Shih Tzu breed or lion dog is characterized by its long, flowing double coat; sturdy build; intelligence; and a friendly, lively attitude. In breeding all coat colors are allowed. The Shih Tzu's hair can be styled either in a short summer cut, or kept long as is compulsory for conformation shows. Although Shih Tzu owners do not generally find fur on furniture or cloths, they do shed small amounts of fur and are a hypoallergenic pet. The shedded hair are usually trapped in the Shih Tzu's dense undercoat until the Shih Tzu starts to do activities that involve a lot of movement (e.g. Running around.)
The AKC Shih Tzu breed standard calls for the dog to have a short snout, large eyes, and a palm-like tail that waves above its torso. The ideal Shih Tzu to some is height at withers is 9 to 10 1/2 inches. The dog should stand no less than 8 inches and not more than 11 inches tall. The Shih Tzu should never be so high stationed as to appear leggy, nor so low stationed as to appear dumpy or squatty. Regardless of size or gender, the Shih Tzu should always be solid and compact, and carry good weight and substance.
James E. Mumford described the breed in an American Shih Tzu magazine, giving a picture of the versatile character of the Shih Tzu: "Nobody knows how the Ancient Eunuchs managed to mix together…And now here comes the recipe: A dash of lion, several teaspoons of rabbit, a couple of ounces of domestic cat, one part court jester, a dash of ballerina, a pinch of old man (Chinese), a bit of beggar, a tablespoon of monkey, one part baby seal, a dash of teddy bear and the rest dogs of Tibetan and Chinese origin."
Due to its popularity the Shih Tzu has been a trend of Designer Dogs and breeding for the same traits in the ASTC standard. This practice is growing because of the demand for smaller easier to carry dogs. The cidclub.com has the same standard as the ASTC but prefers the variation of the breed to be lighter in weight. Called " Imperial Shih Tzu 'or the " Chinese Imperial Dog".
In the grand tradition of all pure-bred dogs, the Chinese Imperial Dog evolved from another breed; in this case it was the Imperial Shih Tzu. They weighed around 3 to 7 pounds and were perfect little lap dogs. The shih tzu standard requires them to be from 9 to 16 pounds.
Imperial Tea-cup: shih tzus that are bred to be smaller than the breed standard or might be specimens of the best and smallest of a litter.
Shih-poo: a cross breed between a shih tzu and a Poodle.
Shizapoo: alternate name for a shih-poo.
The Shih Tzu is easy to care for, but the area around the eyes should be cleaned gently each day. Most Shih Tzus enjoy exercising outdoors and, when exercised regularly, have plenty of stamina. Most enjoy a long walk, although they are also quite happy to run around the house. A dog whose coat is allowed to grow out needs daily brushing to avoid tangles; a short haircut avoids this extra level of care. However, these dogs do not tolerate cold temperatures well, so longer hair during the colder seasons is more appropriate. Shih tzus are considered to be brachycephalic (snub-nosed) dogs. As such, they are very sensitive to high temperatures. This is why airlines that ship dogs will not accept them for shipment when temperatures at any point on the planned itinerary exceeds 75 degrees Fahrenheit (24°C).