Horses are highly social animals that suffer significantly when kept alone, yet single-horse keeping remains common in UK private ownership.
The social needs of horses are frequently underestimated in private keeping contexts where single-horse ownership is the norm. Horses kept alone suffer chronic loneliness that manifests as stereotypic behaviours, heightened reactivity, and impaired learning. The development of stereotypies including crib-biting, weaving, and box-walking indicates chronic stress that has a neurological basis and cannot be reversed once established. Companion animals including donkeys, goats, or sheep provide partial social support, while suitable equine companions are optimal. The welfare case for requiring companion animals for horses is clear, and some European countries are beginning to reflect this in animal welfare legislation.