Stereotypic behaviours in horses arise from chronic frustration of natural behaviour needs and once established are essentially permanent. Understanding their causes informs prevention and the welfare-consistent response to affected horses.
Horse stereotypies are among the clearest behavioural evidence that management practices can cause lasting neurological changes in horses — the equine equivalent of the repetitive self-stimulatory behaviours seen in other animals kept in severely deprived conditions. Once established, stereotypies persist even when management improves because they appear to involve changes in dopaminergic pathways that make the behaviour intrinsically rewarding. This permanence makes prevention essential: a horse that develops crib-biting at 2 years old from inadequate forage access and social isolation will likely exhibit the behaviour for life. The welfare-consistent response to an established stereotypy is to remove the obstacles to normal behaviour as much as possible — maximising forage, turnout, and social contact — not to prevent the stereotypy mechanically while maintaining the conditions that caused it.