The development and use of facial grimace scales for pain measurement in animals

Neurosci Biobehav Rev. 2020 Sep;116:480-493. doi: 10.1016/j.neubiorev.2020.07.013. Epub 2020 Jul 16.


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: Facial expression; Grimace; Pain; Preclinical; Veterinary.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't