Thumbelina, a 17-inch-tall Miniature horse, has been officially recognized by the Guinness Book of Records as the world’s smallest horse, reports the London Daily Mail.

The 5-year-old mare weighed eight pounds at birth and now tips the scales at 60 pounds. The average Miniature horse stands about 34-inches tall and weighs around 250 pounds.

Thumbelina’s owners told the Daily Mail the mare stopped growing as a yearling. The dwarf Miniature wears orthopedic fittings to help straighten out her legs, which are proportionally smaller than her body and head.

“When she was born, she was so small we thought she wasn’t going to make it,” Michael Goessling told the Daily Mail. Goessling’s parents have been breeding Miniature horses on their St Louis, Mo., farm for 15 years.

“My parents have bred hundreds of Miniature horses, but we have never had one as small as Thumbelina,” Goessling said. “She was just a complete fluke, and we call her a mini mini.”

Goessling told the Daily Mail they decided not to breed the tiny mare, due to the high risk of complications.

“And although we love Thumbelina, we do not think it is right that the gene which creates dwarfism in horses is carried on through future generations,” Goessling said.

To read the Daily Mail’s coverage of the story and see a photo of Thumbelina, click Meet Thumbelina, the world’s smallest horse (Oct. 8)