Blood sampling from the retro-orbital plexus, the saphenous vein and the tail vein in rats: comparative effects on selected behavioural and blood variables

We compared the behaviours of rats, and measured various blood parameters, after three blood sampling techniques: orbital puncture while they were und er diethyl-ether anaesthesia, blood collection by tail vein puncture under O-2-N2O-halothane anaesthesia and puncture of the saphenous vein without an aesthesia. Twelve rats were subjected to the three treatments according to a Latin square design. After each treatment, the behaviour of the rats was automatically monitored using the so-called LABORAS(TM) method, which discr iminates between grooming, locomotion and inactivity in rats. Based on exci tation scores and urine production, it was found that induction of diethyl- ether anaesthesia combined with orbital puncture caused more distress than did the other two blood sampling techniques. The three techniques had no di fferential effects on the behaviours of grooming, locomotion and inactivity . Collecting 0.5 ml of blood by orbital puncture was +/-7 times faster than doing so by saphenous vein puncture and +/-15 times faster than collecting blood by tail vein puncture while the rats were under O-2-N2O-halothane an aesthesia. The levels of some haematological and plasma variables differed significantly between the three blood collection techniques. These observat ions may help to select the most appropriate technique of blood sampling wi th respect to anticipated discomfort in the animals.