Wikipedia description of miniature horses:
Miniature horses are found all over the world and come in various colors and coat patterns. The designation of miniature horse is determined by the height of the animal, which, depending on the particular registry involved, is usually less than 34–38 inches (86–97 cm) as measured at the withers. While miniature horses are the size of a very small pony, many retain horse characteristics and are considered "horses" by their respective registries.
Miniature horses are friendly and interact well with people. For this reason they are often kept as family pets, though they still retain natural horse behavior and must be treated like an equine, even if they primarily serve as a companion animal. They are also trained as service animals, akin to assistance dogs for people with disabilities. While miniature horses can be trained to work indoors, they are still real horses and are healthier when allowed to live outdoors (with proper shelter and room to run) when not working with humans.
They are generally quite hardy, often living longer on average than some full-sized horse breeds; the average life span of miniature horses is from 25 to 35 years.
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