Blood Collection in Rodents

General Information

• The acceptable quantity and frequency of blood sampling is determined by the circulating blood volume and the red blood cell (RBC) turnover rate.  Excessive blood collection may result in hypovolemic shock, physiological stress and even death.
• Blood draws should be limited to the lowest amount consistent with the needs of the research.  Maximum blood volumes should be taken only from healthy animals.
• Personnel performing blood collection procedures MUST be appropriately trained and experienced with the techniques being used.  If you are not experienced in blood collection technique and need training, ULAR can provide training - visit the ULAR Website and choose "Training" for more information and links to online tutorials.

Policy

The maximum amount of blood that can be drawn from a rodent in any 2-week period may not exceed 1% of the animal's body weight.  For example, for a mouse weighing 25 grams, the maximum allowable blood collection may not exceed 0.25 grams or 0.25 ml.

If the maximum amount (1% of body weight in blood, as defined above) must be drawn all at once or via multiple draws over a 24-hour period, replacement fluids (sterile 0.9% saline or Lactated Ringers Solution) should be administered.  The volume/amount of fluid replacement recommended is equivalent to the volume of blood drawn.

Exsanguination:  It is possible to collect approximately half of the total blood volume at exsanguination.  Total blood volume (TBV) of a mouse is approximately 8% of body weight or 80 µl/g.  Total blood volume for a rat is approximately 6% of body weight or 60 µl/g.