Development and validation of a multidimensional composite pain scale for Rabbit (CANCRS) in a clinical environment

The main objective of this study was to develop a multidimensional composite pain scale for assessing and quantifying pain in rabbits (CANCRS); to this purpose, Rabbit Grimace Scale (RbtGS) and a scale including clinical parameters (CPS) were merged; the two scales performances were also evaluated individually, in order to validate RbtGS in a clinical setting and to verify clinical parameters usefulness in detecting pain. Rabbits (n=116) were evaluated by two raters, who could be veterinarians (V) or veterinary medicine students (S). Raters were asked to report the time needed for any evaluation and a total score, in order to define a pain class. Pain classes (No pain, Discomfort, Moderate pain and Severe pain) matched presumptive pain classes and accordingly, the validity of the three scales was measured using Chi-square test. Patients (n=69) were evaluated by one V and one S, allowing to assess the impact that the experience has on the results. Inter-rater reliability was tested for each scale using intra-class correlation coefficient (ICC) and for each parameter of the CANCRS using Cohen’s kappa. Validity results show that only CANCRS and RbtGS efficiently reveal pain, but both tend to underestimate it. Inter-rater reliability was very good for both CANCRS and CPS, suggesting that experience has little influence on the results; rater’s experience has a greater impact using RbtGS. Inter-rater agreement was at least good for each parameter. In conclusion, CPS alone is neither effective or reliable in quantifying pain. The RbtGS is a useful tool in clinical practice, when coping with many rabbit breeds; however, training is beneficial for a better use of the scale. The CANCRS is easy and fast to use and enrich RbtGS with some clinical parameters that should be monitored during any clinical examination, leading to a more exhaustive evaluation of the patient.