Where is rat blood taken from? - briefly
Blood is usually drawn from a rat’s tail vein or the saphenous vein of the hind limb.
Where is rat blood taken from? - in detail
Blood samples from laboratory rats are obtained from several well‑characterized anatomical locations. The choice of site depends on the required volume, frequency of sampling, and the physiological impact on the animal.
The most frequently used points are:
- Tail vein (lateral or dorsal). Accessible without surgery, suitable for volumes up to 0.5 ml per session. Warm the tail to dilate vessels, then insert a 23–27 G needle at a shallow angle. Suitable for repeated sampling when the animal is restrained gently.
- Saphenous vein (medial hind‑limb). Allows collection of 0.2–0.3 ml without anesthesia if the animal is briefly restrained. The vein is visualized by shaving and gently pulling the skin taut. This site supports moderate‑frequency sampling.
- Retro‑orbital sinus. Provides up to 0.5 ml per draw. Requires anesthesia (isoflurane or injectable) and a fine glass capillary or heparinized micro‑hematocrit tube. Offers rapid collection but carries a higher risk of ocular injury; therefore, it is limited to terminal procedures or low‑frequency sampling under strict ethical oversight.
- Jugular vein. Accessed via a small cervical incision under general anesthesia. Yields up to 1 ml per collection and supports serial sampling through indwelling catheters. Suitable for chronic studies where repeated large volumes are needed.
- Femoral artery or vein. Exposed through a groin incision under anesthesia. Provides arterial or venous blood respectively, with volumes up to 0.5 ml. Useful when arterial blood gases are required.
- Cardiac puncture. Performed after deep anesthesia or euthanasia. Allows collection of 1–2 ml of blood from the left ventricle. This method is terminal and provides the maximum volume with minimal hemolysis.
General guidelines applicable to all sites include:
- Limit total blood withdrawn to no more than 10 % of total circulating volume (approximately 6–8 ml for a 250 g rat) within a 24‑hour period.
- Use heparin‑ or EDTA‑coated collection tubes to prevent clotting.
- Apply gentle pressure after needle removal to minimize hematoma formation.
- Maintain aseptic technique to avoid infection.
- Record the exact site, volume, and any anesthesia used for reproducibility and compliance with animal welfare regulations.