Assessment of pain and stress in rabbits during blood collection procedure from the middle ear artery

BACKGROUND: Middle ear artery blood collection in rabbits can cause pain/stress. AIM AND OBJECTIVE: As there is no direct measurement of pain/stress in laboratory rabbits during blood collection, we attempted to develop a scale using four different assessment items. MATERIALS AND METHODS: Fifty-two New Zealand White rabbits which have been used for ongoing research, were considered for this study. As per the ongoing study, blood samples were collected at predefined time points. During blood collection, rabbits were observed, and following items were recorded: 1)Rabbit Grimace Scale (RbtGS) before the sampling, 2)Number of needle pricks required, 3)Presence/absence of hematoma, 4)Size of hematomas. Responses for each item were numbered with a Likert scale. Values of four items were summed up and converted into an analogous scale of 1-10. Internal consistency of four items was assessed using Cronbach’s-α. RESULTS: Four scale item measurements showed a good internal consistency. Based on the recordings it showed 37% of rabbits expressing RbtGS-0 on day 0 gradually increased to 50% until day 90 and slightly reduced afterward. The total number of needle pricks required for sample collection gradually reduced with continuation of samplings. Percentage of hematoma formation was 33% on day 0 and <25 on subsequent days. A reduction in number of needle pricks and hematoma formation indicated a reduction in level of animals’ resistance to the procedure. CONCLUSION: New scale appears to be a good method to assess the pain/stress during ear artery bleeding in rabbits and can be used as a guide to improve refinement and welfare of the rabbits.