How to draw blood from a rat? - briefly
Use a sterile 27–30 G needle to puncture the warmed rat’s lateral tail vein and draw the required volume into a heparin‑treated capillary tube. Apply proper restraint, maintain aseptic technique, and follow institutional animal‑care regulations.
How to draw blood from a rat? - in detail
Collecting blood from a laboratory rat requires strict adherence to aseptic technique, animal welfare regulations, and precise methodology. The following protocol outlines each stage of the procedure.
Equipment and supplies
- Sterile 27‑30 G needle or micro‑hematocrit capillary tube
- Heparin‑ or EDTA‑coated microcentrifuge tubes (0.5–1 mL)
- Isoflurane vaporizer or injectable anesthetic (e.g., ketamine/xylazine)
- Heating pad to maintain body temperature
- Alcohol swabs (70 % isopropyl)
- Sterile gauze pads, cotton wool, and adhesive tape
- Sharps container for disposal
Preparation
- Verify Institutional Animal Care and Use Committee (IACUC) approval and confirm the animal’s identification.
- Fast the rat for 2–4 hours if required by the experimental design; provide water ad libitum.
- Calibrate anesthesia delivery system; confirm depth of unconsciousness by lack of pedal reflex.
- Warm the animal on a heating pad for 5 minutes to prevent hypothermia during sampling.
Site selection
- Tail vein: suitable for volumes up to 0.5 mL, minimal invasiveness.
- Saphenous vein: allows repeated sampling of up to 0.2 mL.
- Retro‑orbital sinus (under deep anesthesia only): permits larger volumes (0.2–0.5 mL) but carries higher risk.
Technique (tail vein example)
- Position the rat ventrally on a slanted platform; secure gently with tape to expose the tail.
- Apply a warm water bath (37–38 °C) to the tail for 30–60 seconds to dilate vessels.
- Disinfect the puncture site with an alcohol swab; allow to air‑dry.
- Stretch the tail skin taut with one hand; insert the needle bevel up at a shallow angle (10‑15°) into the lateral vein.
- Aspirate gently with a 1 mL syringe; collect the required volume into the pre‑labeled tube.
- Apply pressure with sterile gauze for 30 seconds to achieve hemostasis; inspect for continued bleeding.
Technique (saphenous vein example)
- Place the rat in a restrainer that exposes the lateral thigh.
- Palpate the saphenous vein just distal to the knee; immobilize with a small clamp if necessary.
- Follow steps 3–6 of the tail‑vein method, adjusting needle angle to align with the vein’s orientation.
Post‑procedure care
- Return the animal to its cage; monitor until full recovery from anesthesia.
- Record volume, collection site, and any complications in the animal’s log.
- Provide analgesia if surgical trauma is suspected (e.g., buprenorphine 0.05 mg/kg subcutaneously).
Safety and troubleshooting
- If blood flow is absent, rewarm the limb or select an alternative site.
- Hemolysis may indicate excessive force during aspiration; reduce suction speed.
- Persistent bleeding requires additional pressure, a hemostatic agent, or temporary compression with a bandage.
Adhering to this protocol ensures reliable sample acquisition while minimizing distress and physiological impact on the rat.