A comparison of various methods of blood sampling in mice and rats: Effects on animal welfare

This study was conducted to investigate the effects of blood sampling on animal welfare in a total of 60 NTac:SD rats and 72 C57BL/6NTac mice of both sexes. Blood was sampled either by sublingual vein puncture, tail vein puncture or by retrobulbar plexus/sinus puncture under light isoflurane anaesthesia and, additionally, by facial vein puncture in mice. Non-punctured animals as well as isoflurane-anaesthetised animals were used as controls. Pre- and post-puncture sucrose intake (1.5% w/w) was measured in rats, and nest building scores were studied in mice for 24 h post-puncture. Post-puncture activity and anxiety levels of rats and mice were measured using an elevated plus maze test and an open field test. Stress levels 24 h post-puncture were assessed by analysing faecal corticosteroid metabolites. Sucrose intake and faecal corticosteroid levels were not affected by the blood sampling procedures. Rats showed reduced activity in the open field test and an increased level of anxiety in the elevated plus maze test following retrobulbar plexus puncture and isoflurane anaesthesia. In mice, nest building activity was affected in all the groups compared with the control group, except for animals subjected to facial vein puncture. Retrobulbar sinus puncture, tail vein puncture and sublingual puncture in mice resulted in reduced activity and increased anxiety. We conclude that, of the tested methods, puncture of the tail vein and the sublingual vein have the least adverse effects in rats, whereas facial vein puncture had the least adverse effects on the welfare parameters in mice.