Horses are highly social animals that experience significant welfare compromise when isolated from companions, regardless of management quality in other respects.
Social isolation is a fundamental welfare problem for horses that cannot be compensated by excellent physical care. Horses deprived of conspecific contact show sustained cortisol elevation, develop stereotypies and show generalised anxiety. Stereotypies indicate that the welfare problem has caused lasting neurological change. Prevention requires housing horses with compatible companions from the earliest age. Where individual horses cannot be housed together safely, managed social contact through shared fencing provides significant welfare benefit.