Saphenous vein

Technique

Sampling from the lateral saphenous vein is a relatively quick method of obtaining blood samples from all strains of rat. It does not require the rats to be warmed.

Slides and videos of restraint, shaving and sampling for this technique with mice are available on the websites of the Norwegian Reference Centre for Laboratory Animal Science and Alternatives and the University of Bergen.

Blood is collected from the lateral saphenous vein which runs dorsally and then laterally over the tarsal joint. The site is shaved either with a scalpel blade, using a gentle stroking motion in the direction of the hairs and holding the blade almost parallel to the skin to avoid cutting it, or with electric clippers. Shaving need only be repeated as the hair grows again.

The rat should be restrained either manually or using a restraint tube. This can cause stress and therefore the duration of restraint should be minimised. Where a restraint tube is used, it should be appropriate to the size of the rat. All forms of restraining equipment should be frequently washed to prevent pheromonally-induced stress or cross-infection.

To collect blood, the hind leg should be immobilised in the extended position by applying gentle downward pressure immediately above the knee joint. This stretches the skin over the ankle, making it easier to shave, and immobilising the saphenous vein. An aseptic technique should be used. Anaesthesia is not necessary but may be used on welfare grounds for animals that are difficult to handle. Where sedatives contain peripheral vasodilators, doses should be low to avoid prolonged bleeding from the puncture site. A local anaesthetic cream (e.g. EMLA cream) can be applied to the site 30 minutes prior to blood sampling. The number of attempts to take a blood sample should be minimised (no more than three needle sticks in any one attempt). Blood is collected by capillary action into a haematocrit tube or passively into a tube.

Blood flow can be stopped by gentle finger pressure over the puncture site, or simple relaxation of operator's grip on the animal's leg. Animals should not be returned to their cage before the blood flow has stopped. 

No more than four blood samples should be taken in any 24-hour period. If more samples are needed, then surgical cannulation or temporary cannulation should be considered. For multiple samples the scab or the blood clot should be removed.

Rats can show temporary favouring of the limb following sampling from the saphenous vein.

Summary

Number of samples No more than four blood samples should be taken within any 24-hour period
Sample volume Up to 0.2 ml may be taken for a single sample, which can usually be repeated at 2-week intervals without disturbances to haematological status. Alternatively, multiple smaller samples (e.g. 0.02 ml daily) may be drawn, taking into account limits on sample volume.
Equipment 23G needle or lance
Staff resource One person if a restraint tube is used. Where manual restraint is used, two people are required: one for handling the rat and one for taking the blood sample.
Adverse effects
  • Bruising
  • Haemorrhage
  • Infection
  • Temporary favouring of the limb

Resources and references

Saphenous vein sampling in other animals

Click here for information on saphenous vein blood sampling in the mouseClick here for information on saphenous vein blood sampling in the hamsterClick here for information on saphenous vein blood sampling in the guinea pig

All blood sampling techniques in the rat

Click here for information on blood vessel cannulation in the ratClick here for information on tail vein blood sampling in the ratClick here for information on jugular vein blood sampling in the ratClick here for information on retro-orbital blood sampling techniques in the ratClick here for information on using a temporary cannula for blood sampling in the ratClick here for information on abdominal/thoracic blood vessel blood sampling in the ratClick here for information on cardiac puncture blood sampling in the ratClick here for information on schedule 1 stunning followed by decapitation for blood sampling in the ratClick here for information on decapitation blood sampling techniques in the rat