Research on positive emotional states in pigs - including play behavior, 50kHz vocalizations, and cognitive bias tests - is transforming understanding of pig welfare from absence-of-suffering to presence-of-wellbeing.
The shift to positive welfare science represents a paradigm change in how pig farming is assessed. Early welfare frameworks focused on prevention of negative states - disease, injury, fear, hunger. Modern welfare science adds a positive component: do pigs have opportunities to experience pleasure, play, curiosity, and satisfaction? This matters practically because animals with enriched opportunities for positive experience are also more resilient, better able to cope with challenges, and show better health outcomes. The Five Domains model of animal welfare explicitly includes positive mental states as a welfare requirement, not an optional extra.