Scientific understanding of pain and nociception across animal taxa underpins all welfare policy and practice, and ongoing research continues to expand the circle of animals recognized as capable of suffering.
Pain research in animals directly shapes which beings receive welfare protections and what interventions are considered necessary. The expansion of this circle — from mammals, to birds, to fish, to crustaceans — has been driven by evidence that pain-like processing is more phylogenetically widespread than previously assumed. Maintaining scientific openness to expanding the welfare circle based on evidence, rather than convenience, is the foundation of a welfare science that genuinely serves animal interests.