Tiny teacup terrier Lucy has a superpower - she is the world’s smallest working dog with the BIGGEST heart. The mini Yorkshire terrier stands at just 5.7 inches tall, is only 7.5 inches long and 2.9 lbs in weight. While most working dogs are known for their strength and agility, Lucy holds the Guinness World Record for being the smallest working dog - for her work as a pet therapy dog. Together with owner Sally Montufar, a college teacher from South Jersey, Lucy visits the vulnerable, sick and disabled, bringing them comfort and distraction from the challenges in their lives.