Master Your Blood Sampling Technique in Small Animals

Collection of blood samples from dogs, cats and rabbits is commonplace within veterinary practices. Still, it is essential to ensure best practice is followed to minimise the risk of infection to the patient and contamination of the sample.

Equipment

Ensure you have the following equipment ready before sampling:

• Clippers with a size 40 clean and undamaged clipper blade (quieter if possible)
• Clean kidney dish with several gauze swabs in
• Surgical spirit
• Chlorhexidine
• Two pairs of gloves (do not need to be sterile)
• Blood tubes
• Cotton wool swab
• Appropriate sized syringe, depending upon the amount of blood required – always select the smallest which allows you to collect the necessary amount minimising negative pressure
• 21g needle (if your patient is a neonate or very small, a 23g may be required, but anything smaller than a 21g may haemolyse the sample, so if taking blood for haematology, always use a 21g where possible).

Technique

Venous blood sampling is commonly taken from a jugular vein, although it can be taken from a cephalic or saphenous vein. Here we outline collection from the jugular vein:

• Ask your assistant to restrain the patient in the appropriate way
• Clip the fur off the neck, ensuring a wide enough margin for effective decontamination
• Remove as much of the clipped fur as possible
• Squeeze chlorhexidine onto 2 or 3 swabs in the kidney dish
• Spray surgical spirit on one other swab in the kidney dish
• Wash your hands using the WHO Hand Wash
• Put gloves on
• Scrubbed the clipped area with chlorhexidine swabs in a back and forth motion to remove as much gross contamination from the skin – take care not to make the skin sore – continue until no further contaminant is seen on the used swabs
• Wipe over the scrubbed area with the surgical spirit swab, from insertion site out
• In an aseptic manner, place the needle onto the syringe
• Put clean gloves on
• With your non-dominant hand, raise the vein by placing your thumb into the jugular groove
• Visualise the vein
• With the bevel of the needle facing you, insert the needle into the skin at a 45-degree angle. When you are in the vein, a flash of blood will be seen in the needle hub. Continue to advance the needle until all the needle is inserted into the vein
• Pull back gently on the syringe plunger to allow the syringe to fill – continuing to raise the vein
• Once the desired amount of blood has been collected, remove the needle with the syringe still attached
• Ask the assistant to place pressure onto the jugular vein with a clean cotton wool swab
• Remove the needle from the syringe and immediately place the blood into the required tubes, avoiding touching any of them with the syringe, especially the EDTA tube
• Dispose of the needle in the sharps bin and the gloves, swabs, cotton wool and syringe in clinical waste.

Rabbits

Blood sampling rabbits is usually performed from a marginal ear vein or lateral saphenous vein. Marginal ear veins often collapse when large amounts of blood are required, so the lateral saphenous is preferable.

Jugular sampling is possible, but many rabbits have large dewlaps, inhibiting access to the jugular vein. Equally, many rabbits do not like having their neck extended, especially if they have respiratory disease. If a marginal ear vein or lateral saphenous sample is taken, the assistant will need to raise the vein, but the equipment and collection technique is otherwise very similar.