Date: Revised July 2009
Reference:  Administrative Panel on Laboratory Animal Care

DIRECTIONS: Review the following material. Keep copies of guidelines with applicable protocols. You may find it helpful to post a copy of these guidelines in your laboratory. Questions should be forwarded to the APLAC office, 723-4550.

TRAINING: Training in these techniques and the humane treatment of laboratory animals during the procedures is taught by the Veterinary Service Center (VSC) staff. All new personnel who will be performing these techniques should contact VSC staff for training (725-9901).

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GUIDELINES FOR BLEEDING TECHNIQUES IN RABBITS

1. Use of commercially available rabbit restraint devices is recommended. Adequate care should be taken to prevent injury. Use of an injectable anesthetic such as ketamine and xylazine combinations may supplement or replace a restraint device.
2. The marginal ear vein and central ear artery are the most accessible points for obtaining blood in the rabbit. Use of a topical anesthetic cream is recommended to minimize the discomfort and potential head shaking associated with skin penetration. After drawing from the central ear artery, the site must be compressed manually for at least two minutes to avoid continued bleeding. Additionally, the rabbit should be checked for persistent bleeding 5-10 minutes later.
   
3. Use of topical irritants such as xylene to dilate vessels of the ear pinna is discouraged. If used, the irritant must be immediately removed after bleeding (alcohol followed by soap and water). Vessels can generally be adequately dilated by providing thermal support, such as a heated water blanket or judicious use of a heat lamp, and a brief alcohol prep of the venipuncture site.
4. Use of suction devices applied to the ear is unnecessary and may damage tissues.
5. The volume of blood removed at any one survival bleeding should depend on the frequency of sampling. In healthy rabbits, approximately 10% of circulating blood volume can be safely removed every other week without serious hematological consequences. If weekly bleeding is needed, this volume should be reduced to 7.5% of circulating blood volume. Up to 15% of circulating blood volume may be removed if sampling occurs no more frequently than once every four weeks. Circulating blood volume is approximately 56 ml/kg for rabbits. Using a sampling schedule of every other week, this would correspond to a maximum of 22.5 ml from a 4 kg rabbit. More severe or more frequent bleeding requires monitoring of hematocrit, hemoglobin and total plasma protein, and prior APLAC approval via submission of a revision to the current protocol.
6. Cardiac bleeding requires deep surgical anesthesia. This technique must be limited to terminal collections due to the danger of life threatening complications such as cardiac tamponade, pulmonary hemorrhage, or pneumothorax. Safer alternative techniques for obtaining repeated large volumes of blood are available.

Contact: APLAC Administrator
Last updated: July 2009