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.
Guidelines:The IACUC has provided a set of guidance documents (Policies, Guidelines, and Informational Sheets) for use when planning animal procedures at the University of Iowa. An exception to a Guideline must be described and justified in the Animal Protocol and approved during the normal review process. Purpose: This document provides direction and guidance on appropriate blood collection methods and volumes for animals used in research at the University of Iowa. These guidelines are intended for use by qualified personnel performing blood collection as described on an IACUC-approved Animal Protocol. There are several factors to consider when determining the appropriate blood collection volume and technique. These include:
The sample volume selected should always be the minimum volume of blood which satisfies experimental needs. Appropriate restraint (physical or chemical) should be employed to minimize risk of injury to the animal and personnel. Guidelines for calculation of collection volume:
Maximal blood collection limits are as follows:
Frequent Rodent Calculations
Restraint and anesthesia for blood draws: Restraint methods and anesthesia used to collect blood on research animals must be described and approved in the animal protocol. Examples of restraint devices include rodent restraint tubes, surgical towel or decapicones. Hemostasis: Assuring that blood flow has stopped (hemostasis) is of upmost importance after collecting a blood sample. To achieve hemostasis, place gentle pressure over the site of blood collection to stop the bleeding. A gloved hand and a piece of gauze are commonly used. Best practice involves re-inspecting animals approximately 5 minutes after return to their cage to assure blood flow has stopped. Tail vein collection definitions: Tail vein collection is defined as use of a hypodermic needle or lancet to access the tail vein along the body of the tail. Tail transection is not considered a routine method of blood collection and should be described as a non-surgical procedure with associated monitoring and pain management where appropriate. Techniques for tail vein dilation: The following techniques may be used to increase blood flow on the tail vein of a mouse or a rat: 1) Use of a heating lamp* 2) Submerging the tail in warm water (no warmer than 40oC/104oF) * 3) Placing rubbing alcohol over the tail * Animals under a heat lamp must be under direct supervision and care must be exercised to prevent overheating an animal. Animals that overheat may show an increased respiratory rate, decreased movement, red extremities and avoidance of the heat lamp. Retro-Orbital Sampling: Retro-orbital blood collection in rodents can provide moderate to large amounts of blood when performed by well-trained personnel. However, severe injuries may occur to the animal if this procedure is not done properly, and available alternatives should be used whenever possible. The use of retro-orbital bleeding must be described in the protocol and approved by the IACUC. Because rats have a venous plexus rather than a sinus (as in the mouse), the use of this method may result in greater tissue damage and alternative collection sites are strongly recommended. If retro-orbital collection is necessary, the following guidelines apply:
Application of a topical ophthalmic anesthetic during/after collection should be considered to provide post-procedural analgesia. Last Reviewed by the IACUC 08/10/2022 |
What is the maximum volume of blood that can be taken from a mouse during survival blood collection?
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