Figure 4. Contribution of myocardial infarct size (IS) to pain assessment by traditional welfare score (A) and average Mouse Grimace Scale (MGS) at 24 h postsurgery (B) .

‘Death’ includes all mice that died or were killed before infarct size could be measured. By definition, infarct size is likely to be large in these mice. ‘GA’ denotes mice that received isoflurane general anesthesia but not surgery. Data were analysed using a Kruskal–Wallis test, with Dunn's post hoc test; *P < 0.05, **P < 0.01 and ***P < 0.001. Stock mice, n = 6; GA only, n = 8; sham, n = 5; IS <25%, n = 17; 25% < IS < 40%, n = 7; IS > 40%, n = 10; and death, n = 7. The bars are means ± SEM.