Police dog Dongdong patrols at Chengdu Railway Station in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong sniffs passengers' baggage at Chengdu Railway Station in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong sits on the ground as passengers walk around at Chengdu Railway Station in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong sniffs passengers' baggage at Chengdu Railway Station in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong receives training before performing her duty at Police Dog Base of Chengdu Railway Public Security Office in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong receives training before performing her duty at Police Dog Base of Chengdu Railway Public Security Office in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong gets on a police car to perform her duty at Police Dog Base of Chengdu Railway Public Security Office in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong receives training before performing her duty at Police Dog Base of Chengdu Railway Public Security Office in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong receives training before performing her duty at Police Dog Base of Chengdu Railway Public Security Office in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

A handler combs police dog Dongdong before they perform their duty at Police Dog Base of Chengdu Railway Public Security Office in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong receives training before performing her duty at Police Dog Base of Chengdu Railway Public Security Office in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin) 

Police dog Dongdong receives training before performing her duty at Police Dog Base of Chengdu Railway Public Security Office in Chengdu, capital of southwest China's Sichuan Province, Feb. 20, 2013. It is the first time for the 4-year-old female Labrador to be on duty during the Chinese New Year holidays here and she was responsible for sniffing out explosive devices and materials. (Xinhua/Xue Yubin)