Research showing that pigs experience emotional contagion - catching the emotional states of others - has significant implications for group housing and welfare assessment.
Emotional contagion in pigs means that welfare assessments of individual animals capture only part of the picture. A stressed or fearful pig may spread that state to pen-mates, amplifying the welfare impact of a single negative event. Conversely, positive welfare states - curiosity, comfort, play - also spread through pig groups. Designing enriched environments that generate positive states has multiplier effects on group welfare beyond what individual-animal measures would suggest.