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. Observational case–control study. A total of 86 rabbits, 47 healthy animals and 39 animals with gastrointestinal stasis syndrome (RGIS), participated in the study; of 39 animals with RGIS, 32 animals participated in the second part of the study. In part 1, rabbits underwent pain assessments with VAS and CANCRS. In part 2, the animals underwent four pain assessments with three CANCRS. The first assessment was performed prior to pain management, the others after 30, 60 and 90 minutes. Statistics included Mann–Whitney U test for in-between group comparisons and analysis of variance to assess differences over time. Sensitivity and specificity for each variable of CANCRS were calculated to obtain weighting factors. CANCRS showed differences between healthy and diseased rabbits (p = 0.0001), and median scores were 5 [interquartile range (IQR): 4–6) and 9 (IQR: 7–11), respectively. VAS showed differences between healthy and diseased rabbits (p = 0.02), and median scores were 4 (IQR: 2–5.35) and 5.3 (IQR: 2.65–6.45), respectively. The cut-off scores for CANCRS and 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 CANCRS was significant at each time point. Some variables should be excluded from CANCRS when assessing abdominal pain. CANCRS performed better than VAS, and it detected variations in pain in response to analgesia.