A pleasure craft owner tried to smuggle 23 puppies from Malaysia to Singapore by sea and was caught when a Police Coast Guard officer heard them barking.
Ten of the dogs later died of parvovirus - a contagious illness that affects dogs - while one had to be euthanised.
The vessel owner, Singaporean Cheow Yon Siong, 53, was sentenced yesterday to 20 months' jail.
He pleaded guilty to two offences under the Animals and Birds Act - illegally importing the puppies and failing to ensure that they were not kept in confinement and subjected to unnecessary pain or suffering.
Cheow also admitted possessing methamphetamine and consuming the drug.
He was sentenced to 6½ years' jail last August for drug trafficking, and will serve his latest sentence after completing his earlier one.
The court heard that on Oct 23, 2016, Malaysian Yeun Jian Iun, 23, received a call from a man, known only as Mat, asking him to smuggle puppies to Singapore for $1,000.
Five days later, Yeun went to Cheow's flat in Hougang and the pair took a taxi to Marina Country Club. They then took a pleasure craft to Sebana Cove in Johor to collect six cages containing nine poodles, five shih tzus, four pomeranians, three French bulldogs and two golden retrievers.
The vessel left Malaysia and was on its way back to Singapore around 3.40pm when Cheow sought clearance from the Singapore authorities via walkie-talkie.
About 20 minutes later, Immigration and Checkpoints Authority officers arrived in a boat to collect the two men's passports.
Police Coast Guard Sergeant Muhammad Roshdee Eepsooni heard barking while checking the Singapore-registered boat.
He traced the barking to cargo on board that was covered with large pieces of cloth. The court heard that the puppies were "crammed into rigid pet carriers that were too small" for them.
The case was then referred to the Agri-Food and Veterinary Authority (AVA).
AVA prosecuting officer Yap Teck Chuan said an important purpose of the Animals and Birds Act is to prevent the entry of diseases, especially rabies, into Singapore.
Singapore has been free from rabies since 1953, and the consequences of a rabies outbreak would be dire, he said.
The puppies in this case were from Malaysia, which had an outbreak of rabies in 2015, and which has not been declared free from rabies since.
Yeun was earlier dealt with in court and sentenced to eight months' jail in December 2016.