A composite scale to recognize abdominal pain and its variation over time in response to analgesia in rabbits

To refine a composite scale for pain evaluation in rabbits and evaluate it for pain variations over time. To determine the differences between objective-Centro Animali Non Convenzionali Rabbit Scale (CANCRS) and subjective-visual analogue scale (VAS) in assessing abdominal pain. A total of 86 rabbits participated in the study (n = 47 heathy animals and n = 39 animals with gastrointestinal stasis syndrome - RGIS) and 32 animals with RGIS participated in the second part of the study. In part 1, rabbits underwent pain assessments with the VAS and the CANCRS. The animals included in part 2 of the study underwent four pain assessments with the CANCRS. The first assessment took place before pain management, the others after 30, 60 and 90 minutes. Statistics included Mann-Whitney U test for in-between groups comparisons and analysis of variance to assess differences over time. Sensitivity and specificity for each variable of the CANCRS were calculated to obtain weighting factors. The CANCRS showed differences between healthy and diseased rabbits (p = 0.0001), median scores were 5 (interquartile range - IQR 4-6) and 9 (IQR 7-11) respectively. The VAS showed differences between healthy and diseased rabbits (p = 0.02), the median scores were 4 (IQR 2-5.35) and 5.3 (IQR 2.65-6.45), respectively. The cut-off scores for the CANCRS and for the VAS for differentiation between healthy and diseased rabbits were 7 (specificity 89%, sensitivity 79%) and 4.4 (specificity 59%, sensitivity 69%), respectively. Internal validity testing of the CANCRS showed significancy at each time point. Some variables should be excluded from the CANCRS when assessing abdominal pain. The CANCRS performed better than the VAS and it detected variations in pain in response to analgesia.