Welfare science has moved beyond preventing suffering to actively promoting positive emotional states in farm animals. Pigs are a key research species for understanding positive affect — their emotional complexity makes them ideal welfare subjects.
Pig positive welfare research has transformed understanding of what good farm animal welfare requires. The Five Domains framework now explicitly requires positive experiences — not just absence of negative ones. Research using cognitive bias testing (training pigs to associate locations with rewards or non-rewards, then testing ambiguous locations) shows that pigs in enriched, social, stimulating environments make optimistic judgements — a validated indicator of positive emotional state. Pigs with straw, rooting material, social stability and space show play behaviour, exploration and reduced aggression — all positive welfare indicators. The economic case for positive welfare — healthier pigs, fewer tail biting injuries, better growth — aligns with the animal welfare case.