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The composition and initial evaluation of a grimace scale in ferrets after surgical implantation of a telemetry probe

Lookup NU author(s): Dr Matthew Leach



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Reliable recognition of pain is difficult in ferrets as many currently available parameters are non-specific, inconsistent and/or impractical. Grimace scales have successfully been applied to assess pain in different animal species and might also be applicable to ferrets. To compose a Ferret Grimace Scale (FGS), we studied the facial musculature of ferrets and compared lateral photographs of 19 ferret faces at six time points before and after intraperi- toneal telemetry probe implantation. We identified the Action Units (AUs) orbital tightening, nose bulging, cheek bulging, ear changes and whisker retraction as potential indicators of pain in ferrets. To evaluate whether these AUs could reliably be used to identify photographs taken before and after surgery, the photographs were scored 0, 1 or 2 (not, moderately or obviously present) by 11 observers that were blinded to the treatment and timing of the pho- tographs. All AU-scores assigned to the photographs taken five hours after surgery were significantly higher compared to their time-matched baseline scores. Further analysis using the weights that were obtained using a Linear Discriminant Analysis revealed that scoring orbital tightening alone was sufficient to make this distinction with high sensitivity, specificity and accuracy. Including weighted scores for nose bulging, cheek bulging and ear change did not change this. As these AUs had more missing values than orbital tightening, their descriptions should be re-evaluated. Including whisker retraction, which had a negative weight, resulted in lower accuracy and should therefore in its current form be left out of the FGS. Overall, the results of this study suggest that the FGS and the AU orbital tightening in particular could be useful in a multifactorial pain assessment protocol for ferrets. However, before applying the FGS in practice, it should be further validated by incorporating more time points before and after applying (different) painful stimuli, and different levels of analgesia.

Publication metadata

Author(s): Reigwart ML, Schoemaker NJ, Pascuzzo R, Leach MC, Stodel M, deNies L, Hendriksen CFM, vanderMeer M, Vinke CM, vanZeeland YRA

Publication type: Article

Publication status: Published

Journal: PLoS ONE

Year: 2017

Volume: 12

Issue: 11

Online publication date: 13/11/2017

Acceptance date: 30/10/2017

Date deposited: 21/11/2017

ISSN (electronic): 1932-6203

Publisher: Public Library of Science


DOI: 10.1371/journal.pone.0187986


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