BU IACUCInstitutional Animal Care and Use Committee IACUC oversee... Approved September 2008; Revised January 2014, Revised January 2019, Approved February 2019

All non-terminal blood collection without replacement fluids is limited to 10% of the total circulating blood volume of a healthy animal during a 2 week period. On average, the total circulating blood volume is equal to 5.5 -7.0 % (~66 ml/kg) of the animal’s body weight. If larger amounts are needed, then up to 15 % of the total circulating blood volume may be withdrawn if replacement fluids are given at the time of blood withdrawal. Example: a 4 kg rabbit is calculated to have a total blood volume of 264 ml (66 ml/kg x 4.0 kg). Thus, 26 ml (10% of 264 ml) may be collected without giving replacement fluids and 40 ml (15% of 264 ml) may be collected if replacement fluids are given once every two weeks. Removal of 15% of total blood volume must be justified in the IACUC protocol and approved by the IACUC.

The limitations for blood collection preserve the health status of the animal and maintain the validity of experimental results based on blood samples. The guidelines provided are for healthy, normal adult animals. Animals that are young, aged, stressed, have undergone experimental manipulations, or are suffering from cardiac or respiratory disease may not be able to tolerate this amount of blood loss.



Blood collection sites in mice and rats

The following guidelines refer to the most frequently used survival sampling sites: a) retroorbital; b) mandibular vein; c) saphenous vein; d) tail veins; and e) jugular vein. Blood withdrawal by cardiac puncture is considered a euthanasia procedure and should be performed only after ensuring that the animal is under deep anesthesia, as evidenced by lack of response to a painful stimulus (e.g., toe or tail pinch). A list of the issues that should guide the choice of survival blood collection route(s) is noted below and a link to a summary table (Table 2) is at the bottom of this page.

Methods of blood collection







Fluid replacement

Lactated Ringer’s Solution (LRS) is recommended as the best for fluid replacement. For mice administered 1 ml of warmed LRS IP or SC. For rats administer 5 -10 ml warmed LRS ½ via IP and ½ via SC administration.

Nutritional Supplementation

When larger volumes are withdrawn, especially when there are repeated sampling, it is recommended that rodents receive Nutrical or diet gel as a dietary supplement. For rats and mice, this can easily be done by smearing Nutrical on a few pellets or placing an opened container of diet on the cage floor. Larger, non-rodent species may also be offered easily-digestible and appealing food supplementation.


Training is required for blood collection in any species and by any route. Please contact the BU ASCThe Animal Science Center manages and oversees animal-relate... to schedule training.

Table 2: Summary of Rodent Blood Sampling Techniques

BU IACUC Approved September 2008; Revised January 2014, Revised January 2019, Approved February 2019