Blood sampling is one of the commonest procedures conducted on research animals, but it may cause pain, distress and lasting harm if the technique is poor, or if too much of the circulating blood volume is removed.

The following criteria are a good yardstick for judging the quality of a method for blood sampling:

1. The blood vessel is visible
2. The amount of blood that is removed can be controlled
3. It is quick and easy to prevent any additional blood loss (including internal bleeding) after the sample has been taken
4. There is no risk of damage to the surrounding tissue

Not all methods for bleeding animals satisfy all these criteria.

There are species-specific recommendations for some species on the NC3Rs website. If these cannot be found for the species in which you are interested, there are general rules for amounts to be withdrawn, which may be applied with caution.

Decision trees for blood sampling of mice and rats

The Norwegian University of Life Sciences (NMBU) has produced a range of videos and slide series showing handling, injection and blood sampling techniques on several laboratory animal species (hen, mink, mouse, pig, rabbit, rat).

Please also see this part of the PREPARE guidelines for more references to best practice when taking blood samples. 

More resources

• Resources about handling and procedures from RAT (Research Animal Training)
• NC3Rs Microsite on blood sampling
• Whittaker & Barker (2020): The impact of common recovery blood sampling methods (in mice Mus Musculus), on well-being and sample quality: a systematic review
• Bonnet, El Hassani, Lecq et al. (2016): Blood mixtures: impact of puncture site on blood parameters
• Aasland, Skjerve & Smith (2010): Quality of blood samples from the saphenous vein compared with the tail vein during multiple blood sampling of mice
• Hem, Smith & Solberg (1998): Saphenous vein puncture for blood sampling of the mouse, rat, hamster, gerbil, guineapig, ferret and mink