Siyan has spent the past 11 years finding contraband among the mountains of mail passing through Shanghai's ports. Now, as he enters retirement, his employers hope to find him a new home.

For the first time, the Shanghai Entry-Exit Inspection and Quarantine Bureau has sent out a public appeal to find a family willing to adopt the retired sniffer dog.

Siyan, a 13-year-old American cocker spaniel, has been stationed at each of the city's ports during his career, checking the many parcels and packages that arrive by sea, land and air.

During the past six years, he has found nearly 3,000 animals, plants and other products in the mail that are prohibited from entering the city, according to the bureau. These have included live turtles from Japan, endangered succulent plants from the United States and ivory products.

Last year, despite his advancing age, Siyan detected 871 forbidden items, accounting for one-fifth of all contraband detected at Shanghai ports.

Siyan was recognized as a "five-star quarantine dog" in 2016, making him one of only two dogs to the receive the designation from among the 20 animals used by authorities to sniff out contraband at Shanghai's ports.

He was officially retired on Thursday at a ceremony at the Shanghai Science and Technology Museum, which is when the bureau launched its search for a new home.

"We hope to find a good family willing to adopt this smart and kind dog, to care for him in old age," said Bai Zhanghong, director of animal and plant quarantine supervision for the Shanghai Entry-Exit Inspection and Quarantine Bureau.

Adopting working dogs after their retirement is common practice in many Western countries, but it has yet to become the norm in China due to its relatively short history of using animals in the workplace.

The country's entry-exit inspection and quarantine authorities only started using sniffer dogs in 2001, with the first four going on duty at Beijing Capital International Airport.

In some Western countries, working dogs usually spend their first few months with an adoptive family before receiving training and starting work. They rejoin their families after retirement.

Yet in China, dog training companies are responsible for raising and training working dogs before they are rented to various units. On retirement, if they are not adopted they return to the training company to live out their days.

Responsible pet owners and families are now being urged to open their homes to these hardworking animals.

As many people prefer to adopt puppies, the bureau said Siyan's "pension", which will cover most day-to-day expenses, should allay the fears of potential adopters put off by the thought of caring for an older dog.

However, the authority warned that Siyan, as a working dog, is energetic and needs at least two hours of exercise a day. Candidates also must be over 21, have the consent of their family and a stable job.

Those interested in taking in Siyan have been urged to contact the bureau or museum by April 30, with an announcement expected on May 6.

"These dogs play a major role in improving the inspection accuracy of the detection rate of forbidden articles," said Gong Lindi, who trained Siyan. "I will definitely miss Siyan and hope a good family will offer him a nice home with healthy food."