The organizer of the event, Whitney Ellis, said she stepped away from the kennel around 5:30 p.m. for just a few minutes. When she returned, she said the 4-month-old Yorkie was gone.
Surveillance video at the event, which was held at an ice rink, shows three suspects, two men and a woman, who were playing with the Yorkie. The woman walked away with the dog as the two men kept a look out.
"They had been by earlier in the day and I think they knew exactly what they were doing," Ellis said. "I think they were looking for a moment where someone stepped away."
Over the last two years, Whitney Ellis has been doing independent rescue adoptions that have yielded hundreds of adoptions.
Ellis has contacted police, but said the suspects can return the dog, no questions asked.
"I'd like them to return the dog, that's all that really matters," she said. "It's about the dog. Bring back the dog and we'll let you off, just bring back the dog."