The development and use of highly reliable and valid facial grimace scales for pain measurement in animals: Grimace scales to measure pain now exist for 10 species

The development and use of facial grimace scales for pain measurement in animals. Jeffrey S.Mogil et al. Neuroscience & Biobehavioral Reviews, July 16 2020, https://doi.org/10.1016/j.neubiorev.2020.07.013

Highlights
• Grimace scales were developed based on pain scales measuring facial expression in human neonates.
• Grimace scales to measure pain now exist for 10 species.
• Grimace scales have high reliability and validity, but can be affected by a number of modulatory factors.

ABSTRACT: The measurement of pain in animals is surprisingly complex, and remains a critical issue in veterinary care and biomedical research. Based on the known utility of pain measurement via facial expression in verbal and especially non-verbal human populations, “grimace scales” were first developed a decade ago for use in rodents and now exist for 10 different mammalian species. This review details the background context, historical development, features (including duration), psychometric properties, modulatory factors, and impact of animal grimace scales for pain.

Keywords: grimacePainfacial expressionveterinaryPreclinical