ObjectivesThe aim of this study was to determine whether feline personality would affect the scores obtained with the Glasgow Feline Composite Measure Pain Scale (CMPS-Feline) and the Feline Grimace Scale (FGS), as well as the mechanical thresholds (MTs), both pre- and postoperatively.MethodsCats scheduled for elective neutering were included in the study. After at least 12 h of acclimatisation, the cats' personalities were classified, based on the Feline-ality Assessment, as either 'independent' or 'social', always by the same investigator. Then, a second independent investigator assigned FGS and CMPS-Feline scores and measured the MTs with a mechanical algometer before (baseline) and after elective surgical neutering. Either a -test or Mann-Whitney statistics, depending on data distribution, was used to compare continuous variables between independent and social cats.ResultsA total of 29 cats undergoing either orchiectomy or ovariectomy were included in the study. Of them, 14 were classified as independent and 15 as social. Preoperatively, the independent cats had higher CMPS-Feline (2.8 ± 1.6;  = 0.014) and FGS (0, range 2-1;  = 0.025) scores than the social cats (1.3 ± 1.2 and 0, range 0-0, respectively). Postoperatively, CMPS-Feline ( = 0.011) and FGS ( = 0.009) scores were higher in the independent cats (3, range 3-5 and 2, range 1-3, respectively) than in the social cats (2, range 1-3 and 1, range 0-1, respectively). MTs did not differ between personality groups either preoperatively or postoperatively. Within personality groups, there were no differences between pre- and postoperative study variables.Conclusions and relevanceFeline personality affects the reliability of both the CMPS-Feline and FGS. This should be considered when these scales are used to assess perioperative pain in clinical cats and to titrate analgesic drugs to effect.