World's Smallest Dog: 12.4 cm (4.9-inch) tallAt 1.4 pounds and 4.9 inches tall, Ducky, a yappy short-coat Chihuahua from Charlton (Massachusetts, USA), holds the Guinness World Record for the world's smallest living dog (by height). Ducky succeeds Danka Kordak of Slovakia, a Chihuahua who measured 5.4 inches tall. The smallest dog ever, according to Guinness, was a dwarf Yorkshire terrier who stood 2.8 inches tall.
World's Smallest Snake: 10.1 cm (4-inch) long
World's Smallest Fish: 7.9 mm (0.3-inch) long
The title, however, is contested by 6.2 mm (0.2 in) long male anglerfish (not technically a fish but a sexual parasite) and the 7 mm (0.27 in) long male stout infantfish .
World's Smallest Horse: 43.18 cm (17-inch) tall
World's Smallest Cat: 15.5 cm (6.1-inch) high and 49 cm (19.2-inch) long
World's Smallest Hamster: 2.5 cm (0.9-inch) tall
World's Smallest Chameleon: 1.2 cm (0.5-inch) long
World's Smallest Lizard: 16 mm (0.6-inch) long
World's Smallest Cattle: 81 cm (31-inch) height
World's Smallest Seahorse: 16 mm (0.6-inch) long