Blood vessel cannulation

Please read the general principles of blood sampling and catheterisation pages before attempting any cannulation procedure.


Blood vessel cannulation should be considered when repeated samples are required, as it avoids multiple needle entries at any one site. It is suitable for use in all strains of guinea pig and can be used to take blood from the femoral artery and vein, carotid artery, jugular vein, vena cava and dorsal aorta. Surgery is required and appropriate anaesthesia and analgesia should be used to minimise any pain caused. Proper aseptic technique should be used to prevent post operative infection.  Guinea pigs should be allowed to regain their pre-operative body weight before blood samples are taken. See this technique below.

The cannula is exteriorised at the nape of the neck (through a jacket and tether system). The jacket can cause swelling and skin abrasion and guinea pigs require regular and detailed observation to identify any problems. The use of a subcutaneous access port may be more appropriate because they eliminate the need for tethering systems during periods when animals are not being sampled from.

The jacket and tether system can restrict free movement and the guinea pigs may need to be housed singly after surgery. The caging, bedding and environmental enrichment need to be appropriate to prevent the tether becoming entangled and the wound contaminated. In addition, the bedding needs to be sand free.

Small cannulas will increase the risk of blood clotting  (large cannulae can abrade the blood vessel wall). To prevent this, the cannula requires regular maintenance, (e.g. Regular flushing with an appropriate lock solution. See our preventing thrombosis page for more information).

Blood should be collected aseptically. Usually, 0.1 - 0.5 ml can be taken per sample. Depending on the sample volume and scientific purpose, up to six samples over a two hour period or up to 20 samples over a 24-hour period may be taken. Sterile saline with anticoagulant should be flushed into the cannula after blood sampling to prevent the blood from clotting. A pin is then inserted into the exteriorised end of the cannula, which stops the blood from flowing. A sterile locking solution can be used to lock the cannula after a series of samples have been taken, allowing flushing to be avoided for a number of days.

The following should be checked daily: 

  • Skin in contact with the jackets should be checked for abrasion.
  • The jacket should be checked for tightness.
  • Wound sites should be checked for infection/bruising/swelling/haemorrhage.
  • The cannula should be checked for patency (without blockage).
  • The weight of the guinea pig (remember weight will include that of the device).

Changes in any of the above may require veterinary advice or treatment, or may indicate that a humane endpoint has been reached and appropriate action should be taken.


Number of samples It is recommended up to six samples may be taken in a two hour period, depending on sample volume.
Sample volume 0.1 - 0.5 ml
Equipment 23G - 25G cannula
Staff resource One person is required to take the blood sample. Further staff resource is required for surgery, post-operative care for as long as necessary for the individual animal, and daily animal observations post-surgery.
Adverse effects
  • Infection 1-5%
  • Haemorrhage 1-5%
  • Blocked cannula 1-5%
  • Swelling around the jacket 1-5%
  • Skin sores from the jacket 1-5%

Be sure to use our advice on vascular catheters to reduce the incidence of adverse effects.

Other Guinea pigs should be at their pre-operative weight before blood sampling starts.

Resources and references

Blood vessel cannulation in other animals

Click here for information on blood vessel cannulation in the mouseClick here for information on blood vessel cannulation in the ratClick here for information on blood vessel cannulation in the ferret

All blood sampling techniques in the guinea pig

Click here for information on tarsal vein sampling in the guinea pigClick here for information on saphenous vein blood sampling in the guinea pigClick here for information on abdominal/thoracic blood vessel blood sampling in the guinea pigClick here for information on cardiac puncture blood sampling in the guinea pigClick here for information on schedule 1 stunning followed by decapitation for blood sampling in the guinea pigClick here for information on decapitation blood sampling techniques in the guinea pig