The Shih Tzu (lion dog) is a Chinese dog kept by royalty. It's a small, long-haired, toy dog descended from the Lhasa Apso, a temple dog from Tibet. In the past royal Shih Tzus were kept on satin cushions and raised by palace eunochs.
The Shih Tzu has a proud gait befitting its noble heritage, and like most royalty; Shih Tzus are inbred. All Shih Tzus share the same 14 ancestors (7 male and 7 female) from the Empress Dowager's kennels.
The Shih Tzu is so named because it was bred to resemble a lion as the lion played heavily in Buddhism. Lions are not native to China and Tibet so the people there bred their dogs to resemble them. It doesn't look much like a real lion, but it does resemble the lions in Chinese mythology.
The proper spelling of Shih Tzu is Shih Tzu, not Shih-Tzu or Shitzu. The name is Mandarin and means something like "lion boy". Correct me if you speak Mandarin. I'm Cantonese.