Assessing positive welfare in pigs requires indicators that go beyond the absence of suffering to capture play, exploration, and positive social behaviour. Developing validated positive welfare measures is a priority in welfare science.
The development of validated positive welfare indicators for pigs represents the scientific operationalisation of the Five Domains Model's requirement to assess positive experience, not merely the absence of suffering. Current pig welfare assessments predominantly use negative indicators (lameness, skin lesions, tail biting) that detect welfare failures but cannot capture whether animals are experiencing positive states. Validating positive indicators requires demonstrating that they correlate with other measures of positive state (reward system activation, approach rather than avoidance responses, optimistic cognitive bias). Play behaviour frequency is the most reliably validated positive welfare indicator in pigs: play occurs primarily in positive affective states and its absence in environments that should support it indicates chronic stress. Commercial adoption of positive welfare assessment requires field-applicable tools with acceptable time requirements, which remains a research priority.