Dwarfism is a concern within the miniature horse world. Dwarf horses, while often setting world records for size, are not considered to have desirable traits, generally have incorrect conformation, and may have significant health and soundness issues. Therefore, many miniature horse registries try to avoid accepting minis affected by dwarfism for breeding stock registration.
The oldest living horse on record was a miniature horse affected by dwarfism named Angel who lived with the Horse Protection Society of North Carolina and lived to be over 50. The current record holder for the world’s smallest horse is also a horse affected by dwarfism, Thumbelina, who is fully mature but stands 17 inches (43 cm) tall and weighs 60 pounds (27 kg). Though she has received considerable publicity, her owners have publicly stated that she will not be bred. In 2010 a 6 pound miniature horse foal named Einstein challenged Thumbelina for the title of the World’s Smallest Horse in part based upon the idea that there should be a separate world record category for the smallest non-dwarf horse.