Play behavior in pigs is a reliable indicator of positive welfare states and occurs when animals feel safe, are well-nourished and have appropriate social and environmental conditions.
The documentation of play behavior in pigs provides compelling evidence that these animals experience positive emotional states — not just the absence of negative ones. Play is resource-intensive and serves no immediate survival function; animals only play when their basic needs are met and they feel safe. A pig jumping, chasing, and engaging in mock combat with a herd mate is expressing something that parallels what we recognize as joy or exuberance in children. The welfare implication is that animal welfare should aspire to provide conditions where animals can play, not just conditions where they are not suffering. This higher standard is achievable in pig production with appropriate housing and enrichment.