Shih Tzu Standard # 3

History
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 it's 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.

American and European Shih Tzu
There are differences between the American and European Shih Tzu The FCI standard, which is used in Europe, And then the AKC standard.

References
Coile, Caroline, Ph. D., Encyclopedia of Dog Breeds, Barron's Educational Series, 2005. Page 248.