Volume

The maximum acceptable amount of blood removed from an animal is based on total blood volume (TBV) and the need to avoid physiologic changes in response to blood loss. Estimates of TBV vary greatly and range from <40 to >90 ml/kg body weight depending on species. The NC3R's site provides a table showing practical blood sample volumes for laboratory animals, domestic species and non-human primates. In general, removal of <10% of TBV not more than every 2-3 weeks will avoid adverse effects and allow adequate physiologic recovery time. However, TBV can be significantly lower than mean estimates in animals that are older, obese or otherwise physiologically abnormal.

For rodents: A safe guideline for total maximum volume of blood to remove from a healthy animal is 1% of body weight (BWT) either as a single collection or as multiple collections over a 2 week period.

For example, using the 1% of BWT guideline, a mouse that weighs 25 gm could have either 0.25 ml of blood withdrawn at a single sampling or a total of 0.25 ml of blood withdrawn in multiple samplings over a 2 week period. Note that if the total volume is withdrawn as a single collection it is recommended that replacement fluid therapy  be provided to the animal (not >1.0 ml SQ or IP injection of sterile isotonic fluid such as lactated ringers or 0.9% NaCl). More detailed information on methods of blood collection in laboratory animals is available from the NC3R's site.

ARP personnel are available to provide training and discuss blood collection techniques for your experiment. Contact ARP for more information and training on performing these procedures.

Common sites for blood collection in the mouse

• Ventral jaw (submental) - anesthesia not required
• Saphenous vein - anesthesia not required; multiple samples
• Tail tip - small amounts of blood only
• Lateral tail veins - small amounts of blood only; multiple samples
• Cardiac puncture - terminal procedure
• Submandibular vein - anesthesia not required; adverse effects can occur

Common sites for blood collection in the rat

• Saphenous vein - anesthesia not required; multiple samples
• Lateral tail veins - anesthesia not required; multiple samples
• Gingival vein - anesthesia required; best results with inhalation anesthesia
• Cardiac puncture - terminal procedure

Common sites for blood collection in the hamster

• Gingival vein - anesthesia required; best results with inhalation anesthesia
• Lateral saphenous/lateral tarsal vein - small amounts of blood only; anesthesia required for restraint
• Cardiac puncture - terminal procedure

References:

Diehl K et al. A Good Practice Guide to the Administration of Substances and Removal of Blood, Including Routes and Volumes. 2001. Journal of Applied Toxicology 21, 15-23.

Hankenson FC. Critical Care Management for Laboratory Mice and Rats. 2014. Boca Raton, FL: CRC Press.