Meet Nancy, a 2.5 pound Chihuahua who can boss around critters significantly bigger than herself.

She has a rocky beginning. Abandoned in 2011 and suffering from a sarcoptic mange, Nancy was taken in by London’s Battersea Dogs Home. There, three week old Nancy was raised by a surrogate mom, a Staffordshire Bull Terrier.

Nancy was adopted by Ali Taylor, head of canine welfare training at Battersea, who helps train rescue Border Collies as sheepdogs. Taylor says that Nancy was always interested in watching the Collies herd sheep. “One day I decided to give her a whirl in the ring and she picked it up straight away,” Taylor remembers. “I started in a very controlled environment but it quickly became evident that Nancy has natural ability and loves herding sheep.”

See for yourself!