External jugular vein

Please read the general principles of blood sampling page before attempting any blood sampling procedure.

Technique

Venepuncture from the external jugular vein is the most common route of blood collection in the pig due to the comparative ease of the technique and the capacity to draw repeat samples of blood at relatively large volumes. While greater volumes can be taken, typically less than 20ml of blood is collected from the animal at any one time due to the stress of handling and restraint the procedure can cause.

The pig needs to be restrained for sampling and this can be stressful. Stress can be minimised by training the animal to cooperate with the procedure and by conducting it in a quiet environment. Pigs are intelligent animals and will remember receiving a reward (e.g. food treat) after the procedure, which can make them easier to handle on subsequent occasions. Positive reinforcement training should be used where possible for all procedures from weighing to procedural work to minimise stress to technician and pig.

The procedure should be carried out aseptically. To limit injury and bruising at the sampling site no more than three attempts should be made. Local anaesthetic cream (e.g. EMLA cream) can be applied to the site 30 minutes prior to blood sampling. The external jugular vein can be accessed in the jugular furrow which is visible after extending the neck and retracting the foreleg caudally. Depending on the size of the pig, a 19-21G needle should be inserted perpendicular to the skin at the deepest point of the jugular groove found between the medial sternocephalic and lateral brachiocephalic muscles. It is vital that the animal is held firmly while the procedure is carried out, as struggling poses a high risk of damage to the jugular vein. Use of a vacuum tube to collect samples can reduce the risk of injury to the animal and operator by limiting the level of manipulation required to draw blood. Be aware that the needles used in vacuum tubes are typically too short to reach the jugular vein in large sows. When sampling from larger animals, ensure the needle is inserted to its full length and gently compress the adipose tissue above the vein to ensure successful venepuncture.

Blood flow should be stopped by applying finger pressure on a gauze pad or other absorbent material placed on the blood sampling site for between 30 seconds and two minutes. The pig should not be returned to its pen until the blood has stopped flowing.

Summary

Number of samples

Up to eight in any 24-hour period dependent on volume

Sample volume

20ml +, depending on the size of pig. A vacuum tube system can be used to collect small samples (e.g. 3 ml of blood).

Equipment

19G - 21G needles for pigs and 20 - 21G needles for minipigs (1" long for minipigs/young pigs and 2" long for larger/older pigs).

Staff resource

Four people are required, three to hold the pig in position (head, stifle and front legs) and one person to take the blood sample. Two to three people are sufficient for minipigs, pigs that are used to the procedure or pigs in slings.

Adverse effects

  • Bruising
  • Infection <1%
  • Haemorrhage <1%

Other

Pigs should be trained to cooperate with blood sampling in order to minimise stress. A reward (e.g. food treat) should be given, where possible, after the procedure.

When sampling from large pigs, correct positioning of the snout rope is important to reduce the potential for injury to the mouth and undue pressure on sensitive nasal tissues.

 

Resources and references

All blood sampling techniques in the pig