Boo Boo (dog)
Boo Boo was the world's smallest dog from 2007 to 2013. She stood at a height of according to the Guinness Book of World Records.
Boo Boo was replaced by Milly, who stood at, who was another Chihuahua, as the World's Smallest Dog. Other contenders for the record included Beyoncé, a Dachshund-Chihuahua mix, and Scooter, a Maltese.