Animal husbandry authorities in Yulin, in the Guangxi Zhuang autonomous region, have prevented more than 1,700 dogs from entering the region as of Friday morning because of a lack of quarantine documents.
Animal rights advocates said they believed most of the dogs were stolen.
Yulin locals celebrate the summer solstice, which falls on Saturday this year, with dog-meat hotpot, lychees and liquor. At least 10,000 dogs are eaten during a typical festival, which has spurred opposition from animal rights advocates nationwide in recent years.
Three vehicles transporting dogs into the region were stopped by the Yulin Animal Husbandry Bureau and turned back, said Zhang Lin, the bureau's chief economist.
The Ministry of Agriculture ruled that there must be a quarantine document for every dog being transported, although the carrier will usually be allowed to enter the region as long as the number of dogs in the vehicle matches the quarantine document, Zhang said.
"One vehicle carried 1,120 dogs, one carried 568 and the other carried 35," he said.
"But we cannot do more about that because there are no laws or regulations that authorize us to punish transporters now in China."
Animal rights groups and dog lovers believe that it's possible that many of the dogs on the three vehicles, as well as those sold in local markets, were stolen. Their investigations showed there are no dog farms near the city.
Guo Peng, director of the research center for animal protection at Shandong University, conducted an investigation in the city at the end of 2013 on the eating of dog meat.