Scientists are interested in whether mice’s facial expressions can be used as an index of pain. To test the idea, they compared the Mouse Grimace Scale (pictured below) with more traditional behavioral measures in examining mice’s levels of discomfort after having surgery on their manhood—er, mousehood.
“The Assessment of Post-Vasectomy Pain in Mice Using Behaviour and the Mouse Grimace Scale,” Matthew C. Leach, Kristel Klaus, Amy L. Miller, Maud Scotto di Perrotolo, Susana G. Sotocinal, and Paul A. Flecknell, PLoS ONE, Vol. 7(4), e35656. DOI:10.1371/journal.pone.0035656. The researchers from Newcastle University and McGill University report:
“This study compared changes in behaviour assessed using both an automated system (‘HomeCageScan’) and using manual analysis with changes in facial expressions assessed using the Mouse Grimace Scale (MGS). Mice [...] were assessed before and after surgery (scrotal approach vasectomy) and either received saline, meloxicam or bupivacaine. Both the MGS and manual scoring of pain behaviours identified clear differences between the pre and post surgery periods and between those animals receiving analgesia [...] or saline post-operatively. Both of these assessments were highly correlated with those showing high MGS scores also exhibiting high frequencies of pain behaviours.”
BONUS: Compare the Rat Grimace Scale.