“Ma’am, we need to draw blood and run some tests. ” You have probably heard similar phrases when taking a sick pet to the veterinarian‘s office. Hearing this phrase with a sick pet, whom to you is your child, can be scary. Understanding the process of drawing blood gives a slight bit of comfort in this typically upsetting phrase. Taking blood samples is an important aspect of veterinary medicine. Many diseases are diagnosed based on serum biochemistry. As a veterinary technician, you must understand the process of drawing blood, known as venipuncture.
In some situations, getting a blood sample must be done quickly and there may be a large amount of stress on you as a technician to do this. A useful method for obtaining a blood sample for the beginning veterinary technician is to draw it from the cephalic vein. I am going to explain the process of taking blood from a dog’s cephalic vein which is located in the canine’s forelimb, known as canine venipuncture. Canine venipuncture is a fairly simple process.
When drawing a blood sample form the cephalic vein you will need several things on hand, including a veterinary assistant to restrain the animal. The supplies needed are a set of electric clippers, alcohol wipes, a syringe, a needle, lavender and marble top blood collection tubes, and vetwrap. The lavender top collection tubes are used for samples of whole blood, or plasma. The marble top tubes are for samples of serum – an amber, watery fluid, rich in proteins which separates out when blood coagulates. 2.
Knowing how to properly restrain a dog is a major part of collecting a blood sample. The person assisting, usually a veterinary assistant, will be the one in charge of restraining the animal while the veterinary technologist or technologist obtains the blood sample. The dog must be restrained so that taking the blood sample will not become a fight. This is for not only the veterinary personnel’s safety, but also the safety of the animal.
To properly restrain a dog the veterinary assistant will first move the dog onto the exam table from the floor, then he/she must place one arm around the dogs back while the dog is sitting and the other arm in a headlock position around the head. Secondly, the area where the blood will be drawn must be prepped. First, using the electric clippers shave the area just below the elbow on the top of the leg. Find the olecranon process, process of the ulna that forms the outer bump of the elbow, and where the leg bends at the elbow joint, shave where the cephalic vein is most prominent. Make sure to shave the fur away as smoothly and evenly as possible to avoid contaminants near the entry site.
Second, use an alcohol wipe to clean the shaved area where blood will be drawn from to remove any dirt or hair that may have been missed. Third, occlude the cephalic vein by having your helper hold off the vein. This is done by placing your hand under the elbow so that the dog cannot move its leg back and taking your thumb over the top of the leg and applying pressure so that the cephalic vein will fill with blood and become more visible. Some dogs will willingly give you their leg and allow you to take a blood sample without much restraint.
Next, make sure to twist the correct needle size onto the syringe tightly so the needle does not slip during the insertion of it into the vein. Selecting the needle size should be based on the size of the dog and the size of the vein. Typically, a 22G needle (blue needle) works for most blood draws. In larger breed dogs, 3 an 18G needle will be better and the blood sample will be obtained much more quickly. Lastly, spray alcohol on the area that is about to be punctured by the needle as this will sterilize the area and prevent any bacteria from entering with the needle.
Sterilizing before entry even after sterilization has been done once will ensure no bacteria, dirt, or hair is left on the skin to enter the puncture with the needle. Grab the leg with your hand that is not holding the needle and place your thumb next to the lateral aspect of the cephalic vein to prevent the vein from moving. Next, insert the needle of the syringe directly over the raised cephalic vein. If you have entered the cephalic vein correctly, a small amount of blood will enter the tip of the syringe. At this point, you should pull back on the syringe plunger and blood should begin to enter.
Pulsate the leg if blood is not entering the syringe very quickly. Your assistant can do this by letting up on the pressure exerted by her thumb on the cephalic vein and then quickly reapply the pressure so that the vein will fill with blood again. Now, remove the needle, but have your assistant release pressure over the vein before doing this. Otherwise, blood will start coming out of where you just inserted the needle. Apply pressure over the venipuncture site for 30 seconds and then apply a cotton ball and vetwrap around the area to maintain pressure over the site.
First, fill the lavender topped tube first (usually halfway) by removing the needle and also the rubber plug on the tube. Squirt a blood sample into the tube. If you do not remove the needle and squirt the blood through the needle, the red blood cells can become damaged and the results of the test may be off. Put the lavender plug back on and rock the tube back and forth. This ensures that the blood mixes well with the anticoagulant that is inside of the lavender topped tube. This tube is for a complete 4 blood count and should not coagulate. Second, jab the needle into the rubber stopper of the marble topped tube.
The top does not need to be removed for this tube because it does not matter if the red blood cells are ruptured since serum is being measured in this sample. Lastly, remove the vetwrap and cotton ball after about 20 minutes. Ensure that the site has closed and will not bleed. Canine venipuncture is one of the most necessary processes in the veterinary field. Collecting blood samples correctly and in a timely manner can be the difference between life and death of someone’s beloved fur baby. Blood samples are needed to diagnose most any disease, they may also be used to check glucose levels in a diabetic dog who needs insulin.