Clinical applicability of the Feline Grimace Scale: real-time versus image scoring and the influence of sedation and surgery

Marina C Evangelista; Javier Benito; Beatriz P Monteiro; Ryota Watanabe; Graeme M Doodnaught; Daniel S J Pang; Paulo V Steagall

doi:10.7717/peerj.8967

Clinical applicability of the Feline Grimace Scale: real-time versus image scoring and the influence of sedation and surgery

PeerJ. 2020 Apr 14:8:e8967. doi: 10.7717/peerj.8967. eCollection 2020.

Authors

Marina C Evangelista¹, Javier Benito¹, Beatriz P Monteiro¹, Ryota Watanabe¹, Graeme M Doodnaught¹, Daniel S J Pang^{1

2}, Paulo V Steagall¹

Affiliations

¹ Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Quebec, Canada.
² Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.

Abstract

Background: The Feline Grimace Scale (FGS) is a facial expression-based scoring system for acute pain assessment in cats with reported validity using image assessment. The aims of this study were to investigate the clinical applicability of the FGS in real-time when compared with image assessment, and to evaluate the influence of sedation and surgery on FGS scores in cats.

Methods: Sixty-five female cats (age: 1.37 ± 0.9 years and body weight: 2.85 ± 0.76 kg) were included in a prospective, randomized, clinical trial. Cats were sedated with intramuscular acepromazine and buprenorphine. Following induction with propofol, anesthesia was maintained with isoflurane and cats underwent ovariohysterectomy (OVH). Pain was evaluated at baseline, 15 min after sedation, and at 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 h after extubation using the FGS in real-time (FGS-RT). Cats were video-recorded simultaneously at baseline, 15 min after sedation, and at 2, 6, 12, and 24 h after extubation for subsequent image assessment (FGS-IMG), which was performed six months later by the same observer. The agreement between FGS-RT and FGS-IMG scores was calculated using the Bland & Altman method for repeated measures. The effects of sedation (baseline versus 15 min) and OVH (baseline versus 24 h) were assessed using linear mixed models. Responsiveness to the administration of rescue analgesia (FGS scores before versus one hour after) was assessed using paired t-tests.

Results: Minimal bias (-0.057) and narrow limits of agreement (-0.351 to 0.237) were observed between the FGS-IMG and FGS-RT. Scores at baseline (FGS-RT: 0.16 ± 0.13 and FGS-IMG: 0.14 ± 0.13) were not different after sedation (FGS-RT: 0.2 ± 0.15, p = 0.39 and FGS-IMG: 0.16 ± 0.15, p = 0.99) nor at 24 h after extubation (FGS-RT: 0.16 ± 0.12, p = 0.99 and FGS-IMG: 0.12 ± 0.12, p = 0.96). Thirteen cats required rescue analgesia; their FGS scores were lower one hour after analgesic administration (FGS-RT: 0.21 ± 0.18 and FGS-IMG: 0.18 ± 0.17) than before (FGS-RT: 0.47 ± 0.24, p = 0.0005 and FGS-IMG: 0.45 ± 0.19, p = 0.015).

Conclusions: Real-time assessment slightly overestimates image scoring; however, with minimal clinical impact. Sedation with acepromazine-buprenorphine and ovariohysterectomy using a balanced anesthetic protocol did not influence the FGS scores. Responsiveness to analgesic administration was observed with both the FGS-RT and FGS-IMG.

Keywords: Analgesia; Feline grimace scale; Ovariohysterectomy; Pain; Pain assessment; Pain scoring; Sedation; Surgery.

Grants and funding

This study was funded by an unrestricted grant provided by Zoetis. Funding was also provided by the Companion Animals Health Fund from the Faculty of Veterinary Medicine of the Université de Montréal, supported by Zoetis and a donation by Ms. Valeria Rosenbloom and M. Mike Rosenbloom. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.