The Przewalski 's horse ( Equus przewalskii or E. caballus przewalskii ) , also known as the Mongolian Wild Horse , or Takhi , is the closest living relative of the Domestic Horse and may in fact be the same species . The taxonomic position of Przewalski 's Horse has always been problematic and no consensus exists whether it is a full species ( Equus przewalskii ) , a subspecies of the wild horse ( Equus ferus przewalskii ) or even a sub-population of the horse ( Equus ferus ) . Studies using DNA have been inconclusive , in part due to crossing domestic horses into the Przewalski 's Horse as well as the limited genetic variation present in the founder population of the Przewalski 's Horse .