The horse (Equus ferus caballus) is the best known species of the equine family. Horses are hoofed mammals that have only one toe on each foot, encased in a large hoof. Long domesticated, horses have been used in a variety of roles from transportation to pets to labor. As they aren't ruminants, they only have one stomach. They also can't vomit, making colic a leading cause of death among horses.
Horses come in a variety of sizes from small miniature horses less than three feet high at the withers (the ridge between the shoulder blades of a four-legged animal) to large draft horses over five feet high. Ponies are a number of breeds of horse commonly characterized by small size and stockier body shape.
Adult males are known as stallions unless they've been castrated, whereupon they're known as geldings (which can apply to castrated juveniles as well. Adult females are mares. Baby horses under one year of age are foals, those between one and two years are yearlings, male juveniles (under the age of four) are colts, and female juveniles are fillies.
The only other living horse subspecies is the Przewalski's horse (Equus ferus przewalskii) of Eurasia.
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A horse is a horse, of course, of course!
And no one can talk to a horse, of course!
That is, of course, unless the horse is the famous Mr. Ed!