Teilmann, A. C., Madsen, A. N., Holst, B. et al. 2014. Impact of blood sampling procedures on the welfare of laboratory mice. American Association for Laboratory Animal Science [AALAS] Meeting Official Program, 600-601. (Abstract #P195).

A previous study showed that blood sampling either automatically, through a catheter, or by puncture of the tail vein is less stressful than facial vein phlebotomy in mice. We decided to investigate how facial vein phlebotomy would affect animal welfare compared with retroorbital blood sampling, which is also commonly used for blood sampling in mice. The study was conducted in male C57BL/6 mice to compare facial vein phlebotomy with retroorbital puncture. Blood was obtained at 2 time points, 1600 and 1800, from either the retroorbital plexus (n = 12), the facial vein (n =12) or from control mice by decapitation (n = 8). No anesthesia was used for any of the blood sampling methods. The samples were analyzed for plasma corticosterone using an enzyme-linked immunosorbent assay. Body weights were recorded pre- and postprocedure, and the food consumption was recorded automatically during 24 h after blood sampling. Cheeks and orbital regions were subjected to histopathology. The hypothesis was that mice subjected to facial vein phlebotomy would express equal or higher stress levels in relation to blood sampling than mice subjected to retroorbital puncture. Acute inflammation was expected in the tissues of both groups of blood sampled mice. Normally distributed data sets were analyzed with analysis of variance and for body weight data repeated measures were taken into account. Data sets that did not follow a Gaussian distribution were analyzed with Kruskal-Wallis H test or a Mann-Whitney U test. Mice sampled by facial vein phlebotomy had elevated plasma corticosterone levels at both time points; whereas mice subjected to retroorbital puncture had not. Both these groups lost weight following blood sampling, but the body weight loss was higher in mice subjected to facial vein phlebotomy. The food consumption was not significantly different between the 2 groups of mice. Subcutaneous hematomas and extensive tissue trauma were found after both blood sampling methods. This study supports the preliminary finding that blood sampling from the facial vein of mice induces the highest stress response compared with other routine blood sampling methods. However, both retroorbital puncture and facial vein phlebotomy had considerable impacts on animal welfare, which must be considered whenever blood samples are obtained.