Stereotypic behaviours in horses (weaving, crib-biting, box-walking) are repetitive, invariant behaviours caused by inadequate environments. They indicate compromised welfare and persist even when management improves.
Equine stereotypies are welfare indicators with a clear causal origin: housing and management systems that deprive horses of species-appropriate social contact, movement and foraging create the conditions in which stereotypies develop. Prevention is far more effective than treatment - once established, stereotypies are neurologically entrenched and cannot be reliably eliminated. Suppression devices that physically prevent the behaviour without addressing the cause are both ineffective (the horse finds alternative expressions) and an additional welfare insult - they add frustration to an already frustrated animal. Management that prioritises social contact, ad libitum forage, turnout and environmental complexity prevents stereotypy development.