The IACUC has developed the following guidelines for bleeding rodents and rabbits. Deviations from these techniques must be approved by the IACUC. Instruction in these techniques can be scheduled through the Campus Veterinarian. Videotapes are also available.

A.   Sites

·         For non-terminal procedures, the orbital sinus or tail veins should be used for collection of blood in rats, mice and the orbital sinus for hamsters. The femoral, saphenous, or cephalic vein can be used in guinea pigs and hamsters. The animal must be anesthetized if the orbital sinus is to be used. The central ear artery is recommended for blood collection from rabbits, although the marginal ear vein can be used if only small volumes are needed.

·         Puncture of the posterior vena cava or the heart can be used only if the procedure is terminal. Decapitation is acceptable in mice and rats, less than 200 gms.

B.   Volume and Frequency

·         When antibody production is involved, pre-immunization blood samples may be useful as negative controls. Subsequent blood sampling should be scheduled to coincide with expected peak levels of circulating antibody.

·         Limits on the volume and frequency of blood collection must be imposed to ensure the well being of the animal. The absolute maximum volume of blood collection allowed during a two-week period must not exceed one quarter of the total blood volume. The blood volume of most species is equal to 5-6% of the total body weight. Thus, a volume of not more than 1.5% of the body weight, or 15 ml/kg of body weight can be withdrawn over a two-week period.

·         If such a schedule is followed for over a two-month period, the hematocrit must be checked. If it is less than 20%, approximately half that of normal, the animal must be rested for a month to allow the hematocrit to return to a more normal range.

C.   Bleeding the Laboratory Rabbit

• A pre-anesthetic such as acepromazine maleate (1.0 mg/kg, IM) is recommended to relax the rabbit, to make handling and restraint easier, and to enhance vasodilation before any bleeding procedure. It should be administered five to ten minutes before the procedure is to begin. InnovarVet may be given (0.15-0.2 ml/kg, IM) as an alternative. Some rabbits respond better to one drug or the other.
• A properly designed rabbit-restraining device should always be used for bleeding procedures to prevent injury to the rabbit and handler. The bleeding procedure should be done in a room other than the room used for housing.
• The use of topical irritants, such as xylene, to dilate vessels of the ear pinna is prohibited. Use of any suction devices on the ear itself is unnecessary and is not allowed without prior approval of the IACUC.
• The medial ear artery or lateral veins can be used. The artery is recommended when large volumes of blood are needed. Prior to bleeding, the hair over the vessel should be plucked or clipped if necessary, and the site swabbed with alcohol. Bleeding is best accomplished with a 21-23 gauge needle on a blood collector set and vacutainer tubes.
• Cardiac bleeding requires general anesthetic. This technique should be limited to terminal collections due to the danger or cardiac tamponade or pulmonary hemorrhage and pneumothorax.

D.   Tranquilizers and Anesthetics

• Innovar-Vet (Droperidol and Fentanyl) (0.15-0.2 ml/kg, IM) - Some rabbits appear to have better vasodilation with this drug than with acepromazine.
• Acepromazine maleate (1.0 mg/kg, IM) - Is a good tranquilizer for use in rabbits. It also promotes vasodilation.
• Xylazine (3-10 mg/kg IM) can be used in rats and mice to provide sedation with some analgesia.
• Carbon dioxide - This is an extremely useful agent for use in rodents. It induces a short-term coma in the animal and is relatively non-toxic to the user. It can be used for euthanasia when given as an overdose.
• Melofane (Methoxyflurane) - May be used as a short-term anesthetic in mice and rats. It must be used under a hood due to its potential for causing nephrotoxicity in people.
• Torbugesic (Butorphanol tartrate, 10mg/ml): Acepromazine maleate (10mg/ml) Mix 1:1 by volume. Give 0. 1 ml/kg, IM or SC. This combination is a good alternative for bleeding rabbits when InnovarVet is not available.

Updated: 12/9/04