- Resources and references
- Blood vessel cannulation technique in other animals
- All blood sampling techniques in the rat
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 rat 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. Further proper aseptic technique should be used to prevent post operative infection. Rats 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) or the base of the tail (via a tail cuff and tether system). The use of a tail cuff is preferable to a jacket as the percentage of adverse effects has been found to be 1% of animals with the tail cuff compared to 5-10% for jacketed models. The tail cuff model also has minimal weight loss after surgery, whilst in the jacketed model the rat takes at least 24 hours to regain pre-operative weight. The use of a subcutaneous access port should be explored as it can 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 rats may need to be housed singly after surgery, which will further negatively affect their welfare. 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 - 0.2 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.
- The tail cuff should be checked for tightness and the tail for swelling.
- Wound sites should be checked for infection/bruising/swelling/haemorrhage.
- The cannula should be checked for patency (without blockage).
- The weight of the rat (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 or up to 20 samples over a 24 hour period, depending on sample volume.|
|Sample volume||0.1 - 0.2 ml|
|Equipment||23G - 25G cannula|
|Staff resource||One person is required to take the blood sample. However, 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.|
Be sure to use our advice on vascular catheters to reduce the incidence of adverse effects.
- Feng J, et al (2015). Catheterization of the carotid artery and jugular vein to perform hemodynamic measures, infusions and blood sampling in a conscious rat model. Journal of visualized experiments: JoVE 95
- Gunaratna PC, Kissinger PT, Kissinger CB, Gitzen JF (2004). An automated blood sampler for simultaneous sampling of systemic blood and brain microdialysates for drug absorption, distribution, metabolism and elimination studies. Journal of Pharmacological and Toxicological Methods 49(1): 57-64
- Bardelmeijer HA, Buckle T, Ouwehand M, Bejinen JH, Schellens JHM, van Tellingen O (2003). Cannulation of the jugular vein in mice: a method for serial withdrawal of blood samples. Laboratory Animals 37 (3): 181-187
- Ling S, Jamali F (2003). Effect of cannulation surgery and restraint stress on the plasma corticosterone concentration in the rat: application of an improved corticosterone HPLC assay. J Pharm Pharm Sci 6(2): 246-251
- Nolan TE, Klein HJ (2002). Methods in vascular infusion biotechnology in research with rodents. ILAR journal 43(3): 175-182.