Police in the southern province of Vinh Long early on Wednesday caught two men carrying 13 dead dogs to slaughterhouses on their motorbikes.
Nguyen Hien Tri, 33, and Nguyen Huu Hien, 37, the two drivers, said they were only paid to deliver the dogs.
Police have not revealed further information. But without certificates of origins, the dogs are supposed to be disposed of as a kind of illegal good.
Vietnam is believed to be the second biggest dog meat consumer in the world, with an estimated five million dogs killed and eaten every year. The figure in China is around 20 million.
The dog meat trade has been a target of strong international criticism as most of the dogs are pets stolen from families and usually tortured and killed in painful ways.
Usually only dog thieves are punished, with a fine. They will only face criminal charges if the stolen dog's value is more than VND2 million, around US$100.
In 2009 the Ho Chi Minh City Animal Health Agency urged the government to regulate the dog meat trade.
But the central Animal Health Agency rejected the proposal, saying no other country does so.