They found that 31 of the canines had already suffocated to death in sacks.
At 6.30am Tuesday, the province's Territorial Defence Volunteer Administration officials arrested Issarapong Saenkhampai, 24, and Sern Nguyen Wan, 23, near the Sai Nopparat Pier in Ban Phaeng district.
The suspects confessed that they had been paid to take the dogs across to Vietnam.
Meanwhile, the 2,000 or so dogs rescued on August 11 are reportedly dying due to crowded and damp conditions at the Nakhon Phanom Animal Quarantine Station. As of Tuesday, only 815 of the rescued dogs were found alive, many of them ill, even though more than Bt20 million has been donated to their cause.