IV Injections

IV injection is one of the most common procedure you will perform as an equine veterinarian. Developing skill in IV injection will reduce the chances of an arterial or perivascular injection. It is worth investing the time to learn to do it correctly.

IV injections in equids are typically performed in the jugular vein on either side of the patient’s neck. Thus, the first step in performing an IV injection is to locate the jugular vein. The jugular vein can be found in/adjacent to the jugular furrow. Occlude (hold off) the vein 3 to 6 inches below where you plan to place your needle. Bear in mind, the needle should be placed in the cranial third of the patient’s neck, therefore you should be occluding the vein about half-way down the patient’s neck. Closer to the head of the horse there is a muscle between the artery and the vein, decreasing the chances of an arterial stick. Once the vein is occluded, watch closely for the gradual rise of the vein above your hand.

If you are having trouble visualizing the vein, try changing the position of the patient’s head. Raising the angle of the head/neck at the poll will “stretch or tighten” the vein which. A tightened vein is less likely to roll or push away from the needle. Over-tightening, however, can flatten the vein, making it more difficult to visualize and hit. Wetting the hair with alcohol will always make it easier to visualize the vein. Ponies, donkeys, foals, and very muscular or thick necked horses, can be more challenging.  When learning, start with a quiet, adult animal with a slighter build. Clipping the hair on wooly creatures can also greatly improve vein visibility.

Once you have found the vein and oriented your needle, place the needle (without syringe attached) quickly, but smoothly through the skin. Once the skin has been punctured, the patient should be less reactive and the needle can be guided at the appropriate angle into the vein. With practice, this will become one smooth motion. We prefer using a 1.5″ 18 gauge needle, however, some people prefer 20 gauge or 16 gauge needles. Using a needle less than 1.5″ is not recommended in adult horses, but may be appropriate in foals. 

Placement of the needle into the vein should always be done with the bevel facing toward you. Correct bevel orientation decreases resistance to skin puncture. Incorrect bevel orientation can cause the bevel to rest flat against the wall of the vein, occluding the lumen of the needle.  If you feel confident that you have placed the needle in the vein but have no “flash” or drop of blood in the hub of the needle, start by occluding the vein and rotating the needle slightly.

If you still are not seeing any blood in the hub of the needle, do not pull the needle out. Take a moment to determine where you think the needle is in relation to the vein.  Is it dorsal (above), ventral (below), superficial to the vein (in the SQ space) or have you gone through the vein and out the other side (too deep)? You can palpate the needle in the SQ space. In a proper IV stick, only ~1/4-1/3 of the needle length should be palpated SQ. Try and redirect the needle toward the vein by occluding the vein with one hand the pulling the needle back part-way without exiting the skin and then advancing it in a new direction toward the vein.

If after several attempts at redirecting, you are still unable to find the vein, pull the needle out and start over. Don’t hesitate to ask for help if you are struggling to find the vein or the horse is not being cooperative. Also, remember that each time a needle punctures anything it becomes dulled.  Dulled needles cause significantly more discomfort.  For this reason, a new needle should always be used each time you poke an unanesthetized patient.

You will see many practitioners place the needle and syringe as a single unit. This method may be appropriate for a skilled practitioner, however, it eliminates the ability to visualize the consequence of an inadvertent arterial stick, in which blood will spurt at high pressure from the needle in rhythm with the heart beating. You cannot distinguish vein from artery by aspiration of blood into your syringe. Therefore, when learning, it is always a good idea to disconnect the needle from the syringe during placement. 

You will know the needle is in the vein once there is blood steadily dripping from the hub, especially when the vein is occluded. Again, ensure the needle has been buried to the hub. After any adjustments to needle placement are made, it is important to again ensure that you are still in the vein by occluding the vein and checking for blood actively dripping from the hub. Failure to bury the needle to the hub can increase the likelihood that your needle will be pushed deeper by the patient’s movement or your hand movement during the injection process and result in an arterial injection. 

Once you have you confirmed proper placement in the vein, connect the syringe to the needle hub. Hold the hub of the needle with one hand and attach the syringe with the other hand using firm pressure and a slight twisting motion. Failure to attach the syringe tightly will result in in becoming disconnected as you try to administer the contents. Also, take care not to move the needle in the horses neck when doing so, which is why once hand must be holding the needle in place at the hub. 

Before injecting the contents, once again, check for needle placement and patency by occluding the vein and aspirating the syringe. Blood should flow easily into the syringe. Release the occlusion and inject the contents into the vein. It is best practice to repeat the process of checking for location and patency following administration of the drug. This ensures that you were in the vein at the start and end of administration. Also, if administering a large volume (>5ml) it is common to check placement midway through the injection. Get comfortable switching between occluding/aspirating and administering/pushing the syringe. When shifting you hand position, focus on maintaining the correct vein/needle/syringe alignment throughout the process. It may help to brace your hand against your patient so that you move with the patient.


11 most common mistakes when learning IV injections

  1. Lack of commitment to the act of needle placement – place needle smoothly and with proper speed
  2. Incorrect location on the neck – needle placement is often too low on neck/away from horse’s head
  3. Incorrect bevel orientation
  4. Blind sticking without visualizing the vein, AKA ‘stick and fish’ technique
  5. Assuming that blood in the syringe indicates correct placement
  6. Needle angle too steep
  7. Needle angle to shallow – resulting in majority of needle SQ with only tip of needle in the vein
  8. Failure to bury the needle to the hub
  9. Too short a needle
  10. Use of a dull needle
  11. Failure to maintain proper needle direction completely parallel to the vein) during placement, aspiration or injection