A Shih Tzu (UK: , US: ; 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. It can be effectively treated with drug therapy. Shih Tzu have a number of respiratory problems related to the shape of their face and head. If not treated, the dog may become blind in the eye that has the cataract. The distinctive large eyes can easily be scratched which may cause an ulcer. The distinctive large eyes can easily be scratched which may cause an ulcer. The dog will normally have the injured eye closed or half closed and may have excessive tears.