A Shih Tzu (UK: /ˌʃiːˈtsuː/, US: /ˈʃiːˌtsuː/; Chinese: 西施犬; pinyin: Xī Shī quǎn literally 'Xi Shi dog', also spelled Shittsu) is a toy dog breed, weighing from 4 to 7.25 kilograms (9–16 lb) when fully grown. The breed was developed in China. In the United States, the Shih Tzu ranked the 15th most popular breed in 2013, falling slightly in popularity since 2012 when it was placed in 11th position. 7 Variations. 7.1 Kennel club differences. 7.1 Kennel club differences.