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NC3Rs: National Centre for the Replacement Refinement & Reduction of Animals in Research
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Grimace scale: Rat

The rat grimace scale features specific facial action units, increasing in intensity in response to post-procedural pain. These can be used as part of a clinical assessment.

Screenshot of the top third of the rat grimace scale poster showing the orbital tightening facial action units

Research has demonstrated that changes in facial expression provide a means of assessing pain in many laboratory species including the mouse, rat and rabbit.

We have produced a poster featuring the rat grimace scale to help familiarise staff with the specific facial action units, and encourage their implementation as a means of welfare assessment.

The action units should only be used in awake animals. Each animal should be observed for a short period of time to avoid scoring brief changes in facial expression that are unrelated to the animals welfare.

Read the original paper

Sotocinal SG et al. (2011). The Rat Grimace Scale: a partially automated method for quantifying pain in the laboratory rat via facial expressions. Molecular Pain 7: 55. doi:10.1186/1744-8069-7-55

Available posters

We have copies of The Rat Grimace Scale poster in a number of languages: English, French, Portuguese, Chinese and Japanese.

Whilst we have previously been able to send hard copies of these posters around the world, we are currently unable to do so due to COVID restrictions.

Therefore we are now able to offer downloadable copies, subject to the T&Cs outlined below.

Download terms and conditions

The proper use of a grimace scale poster requires each of the facial action units to be clear and easily discernible. They therefore must be printed by a professional print service at the full A3 size. Further guidance is included in the cover page which should not be removed from the PDF file.

Any requests to reproduce this poster, or to include it in any publications or training materials, should be directed to enquiries@nc3rs.org.uk. You should include how, why and where the poster will be used so that we can consider your case for approval. It is helpful to include any associated text, so we can see the context in which the poster will be put.

Copyright notice: These posters and their content are owned by the NC3Rs and its partners. The poster should not be adapted, and the content should not be sold or used to generate income.

Papers that validate or use this technique

References

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Read more about why the grimace scales were developed, and download the scales for use with mice and rats.

The mouse, rat and rabbit grimace scale posters layered over each other.