The owner of an award-winning dog is fraught with worry after the young pooch disappeared from the Hartsfield-Jackson Atlanta International Airport on Saturday. Floris Van Essen, owner of the 22-month-old American Staffordshire Terrier, Gale, tells NBC News that this is the “worst thing” he has ever had happen to him.

Gale was supposed to be headed back home to Amsterdam after competing in an event in Kentucky, but someone made a mistake at the airport, and now she is missing. Gale was checked in for a KLM Royal Dutch Airlines flight, but her handlers were informed that she had escaped a short time later.

KLM has conducted an investigation and determined that airport staff “improperly secured” Gale’s cage, allowing her to escape. Efforts to find Gale have been underway ever since she escaped, but she hasn’t been seen since 3:30 a.m. on Monday.

(Photo of Gale via screenshot/NBC News)