Positive welfare: What does it add to the debate over pig welfare?

Since the beginning of the farm animal welfare debate half a century ago, the focus has been on the negative side of animal welfare, with most research studying the harms induced by modern husbandry to animals and how to prevent them. Here we review the trend to investigate what has become referred to as positive animal welfare. We review the main published papers on positive welfare and distil the commonalities and distinctions made in the different approaches to positive welfare. Next, we describe several animal-based approaches for assessing positive welfare in pigs and the limited data available on the current status of positive welfare in modern pig production. Finally, areas are identified where a focus on positive welfare could set future trends in animal welfare research and implementation of better pig welfare on farms.