Grimace scales

We all use facial movement to express pain and suffering and to recognise it in other humans. Scientific measurement of facial expression is in fact widely used to measure pain in infants which cannot express their feelings verbally (Schiavenato, 2008).

Research is now being conducted into the recognition and interpretation of facial expressions in a number of animal species. This will help researchers both to recognise pain and suffering, and also to assess the efficacy of pain treatment.

Grimace scales have been developed for 10 species: the mouse, rat, rabbit, cat, horse, cow, piglet, sheep/lamb, ferret and seal. See Mogil et al. (2020) for an overview. Researchers are working on similar scales for the rhesus monkey.

Similar research has been performed on cows to assess their degree of contentment using a range of welfare indicators, including the size of the white of the eye (Sandem et al., 2002) and the posture of the ears (Proctor & Carder, 2014). Studies have been performed on goats to detect signs of emotions in both positive and negative situations (Briefer et al., 2015).

Recording of an AALAS webinar on the use of grimace scales (Daniel Pang)

A Manual for scoring the Rabbit Grimace Scale.

More resources for planning animal research and testing are available in the PREPARE guidelines.


This page was updated on 05 July 2023

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