Blood Collection in Rodents

General Information

The acceptable quantity and frequency of blood sampling is determined by the circulating blood volume and the red blood cell (RBC) turnover rate. Excessive blood collection may result in hypovolemic shock, physiological stress and even death.
Blood draws should be limited to the lowest amount consistent with the needs of the research. Maximum blood volumes should be taken only from healthy animals.
Personnel performing blood collection procedures MUST be appropriately trained and experienced with the techniques being used. If you are not experienced in blood collection technique and need training, ULAR can provide training - visit the ULAR Website and choose "Training" for more information and links to online tutorials.

Policy

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.

Recommended Methods and General Guidelines for Blood Collection in Mice

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Collection Site	Notes
Retro-orbital Sinus	Survival blood collection procedure General anesthesia is recommended, but can be done with a topical anesthetic by well-trained individuals with IACUC approval. Allow 10 days before re-sampling from the same orbit Ensure adequate hemostasis following the procedure
Lateral Tail Vein	Survival blood collection procedure Warming the tail (e.g., warm compresses) will increase obtainable blood volume Anesthesia not required
Saphenous Sampling (medial or lateral approach)	Survival blood collection procedure Application of petroleum jelly to the site may assist the blood to bead to enhance total volume captured Anesthesia not required
Submandibular Sampling	Survival blood collection procedure Use 20 gauge or smaller needle or lancet (4mm) to control the sample volume Anesthesia not required
Ventral/Dorsal Artery Sampling	Survival blood collection procedure Ensure adequate hemostasis following the procedure Anesthesia not required
Cardiac Puncture	Non-survival procedure Requires deep anesthesia

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Recommended Methods and General Guidelines for Blood Collection in Rats

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Collection Site	Notes
All Methods	General anesthesia is required for most methods of blood collection in rats, to prevent restraint-associated distress to the animals and to ensure accuracy in the procedure Keep anesthetized animals warm during the procedure.
Lateral Tail Vein or Ventral Tail Artery	Survival blood collection procedure Warming the tail (e.g., warm compresses) will increase obtainable blood volume Can be performed on non-anesthetized animal if it is properly restrained.
Tail Snipping	Survival blood collection procedure Can be used to collect a small amount of blood. Use sterile scissors
Retro-Orbital Plexus	Survival blood collection procedure More difficult procedure in rats than in mice Topical ophthalmic analgesic in addition to inhalant anesthesia is recommended Allow 10 days before re-sampling from the same orbit Ensure adequate hemostasis following the procedure
Jugular Vein Sampling	Survival blood collection procedure Typically results in a high quality sample Anesthesia required Shave the fur from the area from which blood will be collected Application of petroleum jelly to the site may assist the blood to bead, enhancing total volume captured
Lateral or Medial Saphenous Vein	Survival blood collection procedure Anesthesia not required, but a second person must manually restrain the awake animal Shave the fur from the area from which blood will be collected Application of petroleum jelly to the site may assist the blood to bead, enhancing total volume captured
Dorsal Metatarsal Vein	Survival blood collection procedure Remove fur from area and prep with alcohol. Application of petroleum jelly to the site may assist the blood to bead, enhancing total volume captured
Cardiac Puncture	Non-survival procedure Requires deep anesthesia Euthanize rat once the required blood is collected

Showing 1 to 8 of 8 entries

References and Additional Guidance:

Guidelines for the Survival Bleeding of Mice and Rats. 2010
McGuill MW, Rowan AN. 1989. Biological effects of blood loss: implications for sampling volumes and techniques. ILAR Journal Vol 31, Issue 4, p. 5-20
Rat - Blood draw video (saphenous vein, cardiac puncture)