At first glance, Reginald (Reggie), the world's tallest living dog, and Pearl, the world's smallest dog, seem like an unlikely pair. The seven-year-old Great Dane from Idaho Falls measures 3.3 feet (1 m) tall, while the four-year-old Chihuahua from Florida stands just 3.59 inches (9.1 cm) high. But a recent playdate showed that when it comes to friendship, size does not really matter.