Research into positive emotional states in pigs has demonstrated that good welfare includes not just freedom from suffering but the presence of positive experiences including play and anticipation.
Positive emotion science in pigs has provided some of the most compelling evidence for the Five Domains model's inclusion of mental state as a welfare domain. Pigs in environments that allow play, exploration, and social interaction show measurable indicators of positive affect: optimistic cognitive bias, play behaviour, and positive social interactions. These are not merely the absence of negative states but genuine positive experiences that constitute welfare benefit. The scientific case for positive welfare — that animals should experience positive states, not just be free from negative ones — has welfare management implications: environments that meet physical needs but provide no opportunity for positive experience are welfare-inadequate even without identifiable suffering.