Tail vein

Technique

Tail vein sampling is suitable for all strains but is more difficult in black or pigmented mice. For competent individuals, it is quick and simple to perform. This technique may require the animals to be warmed in order to dilate the blood vessel prior to taking the sample. This can be stressful and can cause dehydration due to salivation, in addition to increasing metabolic rate, which may affect the experimental data. As a result, other routes such as saphenous vein sampling should be used where possible and, in particular, where there is a need to take multiple samples. View a video of the mouse tail vein sampling technique below.

The lateral tail vein is usually used and 50 ul to 0.2 ml of blood can be obtained per sample depending on the size of the animal and specific requirements. The tail may need to be washed with diluted Hibiscrub (1%) in order to see the blood vessel.

To avoid bruising and damage to the tail, normally no more than two blood samples should be taken per session and in any one 24-hour period. Where it is necessary and justifiable to take more, the use of temporary or surgical cannulation methods should be considered. The number of attempts to take a blood sample should be minimised (no more than three needle sticks in any one attempt) and sufficient time should be given for the tail to recover between blood sampling sessions. Alternate sides of the tail should be used and successive needle punctures moved towards the tail base.

If it is necessary to warm the animal, a warming cabinet should be used (39oC for up to 10 minutes). Mice should be carefully monitored, including checking for signs of dehydration. The time the mouse is in the warming cabinet should be recorded and the cabinet should be calibrated regularly to avoid hyperthermia; digital displays should not be relied upon. It is important to ensure the temperature in the cabinet is uniform and that there are no 'hot spots'. Male mice may need to be warmed singly to avoid fighting.

Mouse tail vein trimmed copyright NC3Rs from NC3Rs on Vimeo.

The lateral tail vein is usually accessed approximately one-third along the length of the tail from the tail tip, moving towards the base of the tail for multiple samples. An aseptic technique should be used. It is recommended that a local anaesthetic cream (e.g. EMLA cream) should be applied to the site 30 minutes prior to blood sampling. Animals need to be restrained which can cause stress and therefore the duration of restraint should be minimised. Where a restraint tube is used, it should be appropriate for the size of the mouse in order to avoid damage to the tail, testes and limbs. All forms of restraining equipment should be frequently washed to prevent pheromonally-induced stress or cross-infection.

Blood flow should be stopped by applying finger pressure on the soft tissue. A finger should be placed at the blood sampling site for approximately 30 seconds before the animal is returned to its cage.

Summary

Number of samples One or two blood samples can be taken per session and in any 24-hour period, depending on sample volume. This limit also applies to microsampling.
Sample volume 50 ul to 0.2 ml
Equipment 25G - 27G needle or lance
Staff resource One person is required to take the blood sample if a tube restrainer is used. For large groups of animals more staff members are required.
Adverse effects
  • Infection <1%
  • Haemorrhage <1%
Other Mice may be warmed, to dilate the blood vessel. Care should be taken to avoid hyperthermia and dehydration

 

Resources and references

Tail vein sampling technique in other animals

Click here for information on tail vein blood sampling in the rat

All blood sampling techniques in the mouse

Click here for information on blood vessel cannulation in the mouse Click here for information on tail snip blood sampling in the mouse Click here for information on tail vessel microsampling in the mouse Click here for information on saphenous vein blood sampling in the mouse Click here for information on retro-orbital blood sampling techniques in the mouse Click here for information on abdominal/thoracic blood vessel blood sampling in the mouse Click here for information on cardiac puncture blood sampling in the mouse Click here for information on schedule 1 stunning followed by decapitation in the mouse Click here for information on decapitation blood sampling techniques in the mouse