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How to Use a Butterfly Catheter

Posted by Flavia Vaduva on Aug 10, 2018 11:31:19 AM
Flavia Vaduva
Flavia Vaduva is a general practice Veterinarian and a blogger for VetTechPrep. She has a passion for veterinary medicine, education and business management. She really enjoys interacting with veterinary students and veterinary professionals. She spends her free time riding horses and traveling to explore new places!


The butterfly catheter is one of my favorite phlebotomy supplies. In my opinion, it is often an overlooked and underutilized tool in your veterinary toolbox that can be very helpful in certain situations.

Take, for example, the case of a fractious cat that needs venipuncture.  Perhaps your staff has already tried to draw blood via the jugular vein or has not yet attempted. Sometimes this is a good time to consider if the patient would be more comfortable and less stressed by having blood drawn from a back leg.

And while a needle and 3cc syringe may do the trick, sometimes having the length and flexibility of the tubing of the butterfly catheter collection system may be just what you need to successfully collect your sample.

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The use of a butterfly catheter is fairly straightforward but may require some preparation, practice and sometimes, the help of another person other than the person restraining the pet and the phlebotomist.


First step- know your anatomy!

Butterfly catheters are often used for venipuncture from the medial saphenous vein in cats. This means you are looking for the vein on the inside of the hind legs.

Now it’s time get your equipment together.

Make sure you have appropriate sized of butterfly catheters. The needles come in different gauges and lengths and can range depending on what your hospital carries. Oftentimes, a 22 gauge needle that is 0.75” in length works for most feline patients, though you always want to compare the vein size and choose an appropriately sized needle.

Gather the syringe(s) you will use. A 3cc syringe often works, though in a very small patient, you may consider using a 1cc syringe to try to avoid collapsing a small vein. Also, have your blood tubes ready to place your sample into them once the sample is obtained. 

Next step- patient positioning is key!

Have your assistant position the patient in lateral recumbency. One of their hands will be holding the bottom front leg and the other hand will be holding the top hindlimb while simultaneously applying pressure to the inside of the bottom hind leg.

Now, using one hand, extend the leg on the bottom, apply a small amount of alcohol and carefully identify the vein. Remove the needle cover and hold the butterfly catheter by its flexible wings; also remove the cap at the end of the tubing, making sure to maintain sterility.

Insert the needle into the vein and once you have established blood flow, attach the syringe to the end of the tubing system and start pulling back slowly and steadily on the syringe plunger.

Once your sample is collected, disconnect the syringe from the tubing and either place your sample in to the appropriate blood tubes or have another person place the samples in the tubes.

Remember- team work makes the dream work!

Use of a butterfly catheter can be very helpful if done correctly. But remember- regardless of the type of phlebotomy tools used, it’s always important to be careful when performing venipuncture to keep you, your coworkers and your patient safe!

With a Butterfly or over-the-needle Catheter

Download this 8-Step guide on how to perform both methods at the 7th or 8th intercostal space. 

Fill out the form below, and we will email you a link to get your PDF.



Topics: Catheter, Buterfly Catheter

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