Guinness World Record's Tallest Living Dog and Smallest Living Dog, Giant George and Boo Boo, pose during a photo call in New York, Wednesday. Giant George, a great Dane, measures over 3 feet 5 inches (104cm) from ground to top of shoulders, 7 feet 3 inches (220cm) from tail to nose and weighs 245 lb (111kg). Boo Boo, a Chihuahua, measures 4 inches (10cm) tall, 6.5 inches (16.5cm) long and weighs 24 ounces (680g).