The Assessment of Post-Vasectomy Pain in Mice Using Behaviour and the Mouse Grimace Scale

Background: Current behaviour-based pain assessments for laboratory rodents have significant limitations. Assessment of facial expression changes, as a novel means of pain scoring, may overcome some of these limitations. The Mouse Grimace Scale appears to offer a means of assessing post-operative pain in mice that is as effective as manual behavioural-based scoring, without the limitations of such schemes. Effective assessment of post-operative pain is not only critical for animal welfare, but also the validity of science using animal models. Methodology/Principal Findings: 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 (n = 6/group) 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 (20 mg/kg meloxicam or 5 mg/kg bupivacaine) or saline post-operatively. Both of these assessments were highly correlated with those showing high MGS scores also exhibiting high frequencies of pain behaviours. Automated behavioural analysis in contrast was only able to detect differences between the pre and post surgery periods. Conclusions: In conclusion, both the Mouse Grimace Scale and manual scoring of pain behaviours are assessing th

Mean Mouse Grimace Scale scores pre and post vasectomy.

<p>MGS scores are presented on the y-axis (± 1SE) for mice receiving 2 ml/kg Saline, 20 mg/kg Meloxicam and 5 mg/kg Bupivacaine with the pre and post vasectomy recordings on the x-axis (^★P = 0.002, ^★★P = 0.000).</p

Ethogram for manual behavioural analysis (adapted from Miller et al. [5]).

<p>Ethogram for manual behavioural analysis (adapted from Miller et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035656#pone.0035656-Miller1" target="_blank">[5]</a>).</p

The HomeCageScan scored behaviours that significantly decreased in frequency from pre to post vasectomy.

<p>The HomeCageScan scored behaviours that significantly decreased in frequency from pre to post vasectomy.</p

The HomeCageScan scored behaviours that were unaffected by treatment or time*treatment interaction post vasectomy.

<p>The HomeCageScan scored behaviours that were unaffected by treatment or time*treatment interaction post vasectomy.</p

The correlation coefficients and P-values for the automated behaviours that were not significantly correlated with the MGS.

<p>The correlation coefficients and P-values for the automated behaviours that were not significantly correlated with the MGS.</p

Ethogram for automated behavioural analysis (adapted from Miller et al. [5]).

<p>Ethogram for automated behavioural analysis (adapted from Miller et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035656#pone.0035656-Miller1" target="_blank">[5]</a>).</p

Relationship between changes in MGS and automatically scored behaviour.

<p>MGS scores of one experienced observer are presented on the x-axis and automatically scored behaviours from pre to post vasectomy are presented on the y-axis; walk left (a), walk right (b), and jump (c).</p