Pain scales enable vets and farmers to measure and track animal pain objectively. Developing and validating species-specific pain scales is one of the most impactful areas of applied animal welfare science.
Pain assessment tools transform animal pain from a subjective impression to a measurable, treatable welfare parameter. Before validated pain scales, the question of whether an animal was in pain often came down to individual clinical judgement — and judgements varied widely, with pain frequently underestimated in stoic species. Grimace scales based on facial action coding — measuring ear position, orbital tightening, and nose changes — can be applied quickly in clinical settings and have demonstrated that many routine procedures and conditions cause more pain than previously recognised. Developing and validating pain scales for new species — particularly fish and invertebrates — is a research priority that could unlock pain management improvements for billions of animals currently without access to reliable welfare assessment.