The three men said they traveled to villages to buy the dogs in trade for goods or collected corpses of dogs killed by passing vehicles on roads.
Working with authorities from the Sakon Nakhon Office of Livestock Development, the special unit said the three suspects were from Baan Pang Kwang village in the provincial seats.
Authorities confiscated 70 kilogrammes of frozen dog meat at a roadside shop, on the banks of an irrigation canal.
The arrest came after local residents complained about their suspects trading for dogs in the area.
The suspects killed the dogs, selling the meat, prompting villagers concern about health and hygiene issues.
The three men confessed that they had been selling dog meat in the area for five months.
The butchered dog were sold for Bt80 a bag for raw meat and Bt100 for cooked meat.
Authorities charged the suspects with illegal trade and butchering animals and carcasses without permits.
Thais do not normally eat dog, but Vietnamese immigrants in Thailand's Northeast brought the custom with them from abroad.