Zhongyang, a 5-year-old sniffer dog trained to detect drugs in passenger luggage, has helped uncover more than 440 grams of meth and 79.9 kilograms of cocaine in 15 smuggling cases since his assignment in 2016 to Qingdao Liuting International Airport in Qingdao, Shandong province.

Zhongyang graduated from a sniffer dog training base in Southwest China's Yunnan province before coming to Qingdao, where he relies on his powerful sense of smell and natural hunting instincts to perform his work.

Ren Haiqing, a 48-year-old customs officer, is training Zhongyang, a 5-year-old sniffer dog, in Qingdao, Shandong province. [Photo provided to chinadaily.com.cn]

To guarantee a reliable performance in missions, he does physical and search exercises every day. The dog runs for more than 30 minutes on a treadmill as a basic exercise, and then he practices catch and throw, jumping over gaps, climbing and sniffing.

Ren Haiqing, a 48-year-old customs officer, is combing the hair of Zhongyang, a 5-year-old sniffer dog. [Photo provided to chinadaily.com.cn]

"Zhongyang likes seeking fun, and training seems never to be boring and difficult for him," said his handler Ren Haiqing, a 48-year-old customs officer.

"However, Zhongyang sometimes is too naughty to obey the rules," Ren added, smiling.

As an encouragement or a reward, Ren throws him a rolled-up towel and plays his favorite game, tug-of-war, which, as always, Ren will let Zhongyang win.

Ren Haiqing, a 48-year-old customs officer, enjoys his time with Zhongyang, a 5-year-old sniffer dog. [Photo provided to chinadaily.com.cn]

Besides intensive training, there are also lighter moments, such as when Ren combs Zhongyang's hair and checks on his health.

"He understands me very well, even if I only give him a few orders," said Ren.

Ren and Zhongyang are workmates but also much like a parent and a child.

Sniffer dogs usually serve for eight to nine years, which means Zhongyang remains in his prime but has about four years left on the job.

"Everyone has to face retirement, including me. I am so happy to be with him through the years, and we will be lifelong friends," said Ren.

Ren Haiqing, a 48-year-old customs officer, is training Zhongyang, a 5-year-old sniffer dog in Qingdao, Shandong province. [Photo provided to chinadaily.com.cn]