Wild animals, whose ancestors have never undergone domestication, are distinct from feral animals, who had domesticated ancestors but now live in the wild. Several populations of feral horses exist, including those in the West of the United States and Canada (often called "mustangs") and in parts of Australia ("brumbies") and New Zealand ("Kaimanawa horses"). Isolated feral populations are often named for their geographic location; in Namiba feral animals known as Namib Desert Horses live in the desert, while the Sable Island Horses are resident on Sable Island, Canada. Feral horses may provide useful insights into the behavior of ancestral wild horses.

The Icelandic horse (pony-sized but called a horse) provides an opportunity to compare contemporary and historical breed appearances and behaviour. Introduced by the Vikings into Iceland, Icelandic horses did not subsequently undergo the intensive selective breeding that took place in the rest of Europe from the Middle Ages onwards, and consequently bear a closer resemblance to pre-Medieval breeds. The Icelandic horse has a four-beat gait called the "tölt", which the rack exhibited by several American gaited breeds equates to.