Veterinary Vertex
Veterinary Vertex is a weekly podcast that takes you behind the scenes of the clinical and research discoveries published in the Journal of the American Veterinary Medical Association (JAVMA) and the American Journal of Veterinary Research (AJVR). Tune in to learn about cutting-edge veterinary research and gain in-depth insights you won’t find anywhere else. Come away with knowledge you can put to use in your own practice – along with a healthy dose of inspiration to remind you what you love about veterinary medicine.
Veterinary Vertex
Rethinking Routine: How Needles Stay Sharp After Vaccine Vial Puncture
Ever wondered if you really need to change that needle after drawing up a vaccine? In this eye-opening conversation, Julia Tawil and Dr. Rachael Kreisler challenge a decades-old practice that most of us have never questioned.
Their meticulously designed study measured exactly how much a needle dulls after puncturing a vaccine vial—and the results might surprise you. Using precise force measurements, they discovered that needle sharpness decreases by less than 20% after vial puncture—well below the threshold considered clinically significant. What matters more? The needle's gauge, brand, and how gently you pierce that vial in the first place.
The implications extend far beyond a single needle. With 76% of veterinary professionals routinely changing needles after vaccine aspiration, this small practice change could significantly reduce medical waste, lower needlestick injury risks, and save time across the profession. A follow-up clinical trial with 75 dogs found no difference in patient response between changed and unchanged needles.
This conversation highlights how scientific inquiry can transform everyday veterinary practices, creating safer, more sustainable clinics without compromising patient care. It's a powerful reminder to question even our most fundamental assumptions and seek evidence for everything we do.
JAVMA article: https://doi.org/10.2460/javma.25.01.0025
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Speaker 2:This is Veterinary Vertex, a podcast that AV made journals. In this episode we chat about how needle sharpness is minimally affected by vaccine vial puncture with our guests Julia Taubel and Rachel Kreisler.
Speaker 3:Welcome listeners. I'm Editor-in-Chief Lisa Fortier, and I'm joined by Associate Editor Sarah Wright. Also, julia and Rachel, on this first day of spring 2025, on this nice recording day so excited to be here with you guys. I've had an interest in this topic for a long time. My second oldest sister has been an oncology nurse for 40 some years and she's the one who taught me like never, ever, ever reuse a needle because of the dullness and the pain that it can cause to your patient. So thank you for taking the time to be with us here today and to educate us on your really cool research.
Speaker 4:Thank you so much for having us.
Speaker 2:Yeah, thank you. I definitely echo what Lisa said. I was also taught the same thing always replace the needle. Never use the same needle that you use to puncture a vial Again, just to help with pain for your patients and also potentially some like microbial concerns as well. So glad to see some evidence behind this and that you guys actually investigate this. So, rachel, your Jabma article discusses how needle sharpness is minimally affected by vaccine vial puncture. Please share with our listeners the background on this article.
Speaker 4:Sure. So in this study we wanted to determine whether a practice which, as you guys know, is pretty common that of changing needles after drawing a vaccine up from a vial was important from the perspective of needle sharpness. And we started out by surveying veterinary professionals and that includes veterinarians, veterinary technicians, anyone sort of who might be involved in drawing up or administering vaccines to get a sense of how common the practice of changing needles actually is and if they change it, why do they change it and also which brands they are commonly purchasing. We then use three different brands in four different gauges to determine whether passing the needle once or twice through a vaccine vial decreases sharpness. And you can measure sharpness using a force gauge. And this is actually we followed the same procedure that's used to test sharpness that needle manufacturers use when they're demonstrating the sharpness of their needles.
Speaker 4:And this force gauge measures how much force it takes to penetrate a standardized material. The force is measured in newtons and I don't know about you, I wasn't really familiar with how much a newton was before conducting this study, but you can think of it as about the amount of force that an apple in your hand exerts. So there's gravity acting on that apple, it's in your hand and you can think about sort of that's the amount of force of one newton. And we also visualize the needles, we scan them with a three-dimensional infinite focus microscope and then we could sort of compare before and afters. So that was sort of our approach to taking it. When we surveyed veterinarians, we found that 76 percent or, pardon me, veterinary professionals, 76 percent do routinely change the needle following vaccine aspiration, and by far their biggest concern was needle dulling. And Julia was the one who conducted the force meter analysis, so I'll let her share the results of that.
Speaker 5:Yeah. So we analyzed 330 needles for the penetration force they required to pass through a standardized material after puncturing the vaccine vial zero times, one times or two times. And our thought process was that the needles passed through the vial septum one time would simulate aspirating a vaccine without a dilutant, and then the needles passed through the vial septum twice would simulate vaccines with a dilutant, and then needles that weren't passed through a vaccine vial at all would simulate changing the needle after drawing up the vaccine. And so what we found is that 29-gauge needles required 45% less force when compared to 20 gauge needles, which just indicates that smaller needles require less force, which is kind of expected and makes sense. But then when comparing brands, our brands B and C require an additional 11% and then 10% of force respectively percent of and then 10 percent of force respectively.
Speaker 5:And what that tells us is that careful selection of gauge size and brands of needles can impact the force required to puncture a standardized material. We also recorded the force required for the needles to pass through the vaccine vial septum, which we refer to as a vaccine vial penetration force or VVPF, refer to as a vaccine vial penetration force or VVPF, and the VVPF increased the peak force through the standardized material by 0.03 newtons for each additional 0.5 newtons during the first penetration, but was not significant for the second penetration, and so for what that means clinically is that you should use a gentle technique when inserting the needle into the vial septum to reduce the force needed to administer the vaccine. The difference, the force required to penetrate the standardized material between passage one or two times through the vaccine vial septum, was less than 20%, and so therefore we can assume that it's insignificant. Great.
Speaker 4:So basically force matters when you're inserting the needle to draw up the vaccine, but as long as you have gentle technique. There was actually I believe it was 9% difference for that first penetration and so usually we want to say if there's going to be a difference that's clinically significant. If we don't have any good reason to pick something else, it's usually they pick a cutoff of about 20%. So as long as you're careful with the penetration, you should be in good shape. We did visually examine the needles also and we saw some defects.
Speaker 4:And of course anything magnified 20 times looks pretty scary, you know, like a dust mite looks like a big monster on high magnification. But when we actually measured the magnitude of the hooks, the biggest hook we could find in the 52 needles that we imaged was about 56 micrometers and we know from human literature that humans at least can't tell the difference between hooks of 50 micrometers. So if you use a new needle or a needle that's been given a hook of 50 micrometers, humans can't tell the difference between the injections with those two different needles. It actually takes hooks up to 150 micrometers, which is about three times what we observed in this study, to detect a small difference in pain score. And then the only thing that we could find associated with these hooks, that we could see on the scans, was again this force used to penetrate the vaccine vial.
Speaker 2:I can add what knowing what a Newton is to my list of things I learned this week, so thank you, and 0.03% of an apple.
Speaker 3:Add that into your Newton.
Speaker 2:Exactly. I'm actually getting ready to promote this article on social, so maybe I'll add that in as well. Learn a fun fact today.
Speaker 4:If you're curious, I spent some time last night looking at what 0.1 Newtons would look like, and that was about two nickels. So that was about two nickels difference that we detected, again, that sort of the force that gravity is exerting on two nickels in your hand. To give you a sense of the difference we found, yeah, that's a little more standard.
Speaker 3:You can get some pretty damn big apples these days, so we have some really good information about the background and study Now, Rachel.
Speaker 2:Yeah, that's a little more standard. You can get some pretty damn big apples these days, so we have some really good information about the background and study.
Speaker 4:Now, Rachel, what are some of the take-home messages from this JAPMA article? Ah, so I would say that you know, if we stop changing needles routinely, we could reduce medical waste, lower the risk of needle stick injuries that we incur when we, you know, recap a needle to remove it and to put a new one on. But we could do this and still maintain the same level of care for animals. So I think it's a small change we could make that, you know, across all of the veterinary practices in the country, could make a big difference in terms of safety, efficiency and sustainability, and I guess, even bigger than that, I would say. I think it's always important to critically examine the practices we follow and make sure they're backed by solid evidence and stay up to date with the literature through resources like JAVMA.
Speaker 3:Yeah, thanks for that pitch. I would say the same. You know, I just expected that this was told to us because there was literature to support it. But you know, you have to go look, I guess. So thank you for bringing that to us report it. But you have to go look, I guess. So thank you for bringing that to us.
Speaker 4:What sparked your interest in this topic of needle dulling through diaphragm puncture, right? So I participated as a vaccinator under the PrEP Act, which that was the act that enabled veterinarians to administer COVID-19 vaccines to people, and so I had to be trained, and as part of the training I received, there was materials from the CDC that specifically mentioned that the needle did not need to be changed after a vaccine was drawn up, and I was like, well, that's hot, so we don't do it for people. And so of course now I'm like well, why do we do it for animals? Provided, but that's of course.
Speaker 4:When I turned to literature and I couldn't find anything, there was stuff about maybe reusing needles for folks who have diabetes. There's quite a lot of study on that but there really wasn't anything in veterinary literature. I teach the public health course at Midwestern University and so I teach about the risks of needle stick injuries and regulated medical waste disposal, so I was pretty familiar with the potential risks and the costs associated with changing needle. So I really wanted to just get this done and add something to the literature so people who are curious or want to promote best practices can actually have some evidence.
Speaker 3:Yeah, I always say to people too you know, it's not just the cost of that needle, somebody has to order that needle, somebody has to stock that needle, somebody has to throw out your medical waste. So you're really doing a huge service to hospitals if they can convince people that you don't need to change a needle two or three times. As Julia said earlier, wants to pull up the diluent. I put the emphasis on a different syllable. Julia Wanted to drop the diluent. So it's a great study and, rachel, you and Julia both said some of the most important or take-home messages. But every time we do a study we're surprised by some finding. What surprised you and Julia from your results in this article.
Speaker 4:I had no idea that the vial puncture technique was going to matter so much and, I'll be honest, I had no idea that brand would make a difference. I'd never thought about either. I just stick the needle in the vial and I order the cheapest syringes.
Speaker 5:Yeah, I agree, when you're working in a hospital setting you're typically not paying attention to how gentle or aggressive you're kind of puncturing that vaccine vial. But our studies showed that that does make a difference.
Speaker 2:It's fascinating. So often with studies, we're left with more questions than answers. So what are the next steps for research in this topic?
Speaker 4:Well, I'm actually very excited to you're going to hear it here. First, we just wrapped up a double-blind, randomized controlled trial of 75 dogs to determine whether there's a clinical difference. Because of course it's all great, you know we have these force meters and newtons and that, but I mean, I think what we all care about is what is the animal experience? And so we used an objective measure of the heart rate. We also did a blinded subjective reaction rating to videos of the dogs getting the injections, and then we also asked the person who gave the injection whether they could guess which needle had been replaced and which one had been used to puncture the vaccine vial. And we didn't find any difference by any of these measures.
Speaker 4:So there was a very small increase in heart rate between the DHPP and the rabies vaccine. My suspicion is that's the location, because we did use the typical locations for the front right shoulder for the DHPP and the rear right rear for the rabies. And then there was also a small increase in heart rate for the second as compared to the first vaccine. I think we can kind of you know, maybe the animal knows what's coming. And we also did see the heart rates on average were correlated with the fear, anxiety or FAS score, but we didn't see any difference whatsoever with the changed or the replaced needles. So I'm very excited we're writing up the manuscript now and we're excited to share the next steps.
Speaker 2:Very cool. It's always nice to hear when you guys have something actually set up for next steps, so awesome. Can't wait to see that out. So this week we actually published our first AJVR Artificial Intelligence Supplemental Issue, which we're super proud of and very excited about, and our listeners can find that on our website. So for this particular topic, Rachel, do you see a role for?
Speaker 4:AI. Well, you know AI is great for pattern recognition and you know, I think that you know, for something like rating the dog's reaction to the injection. It would be something that would be much more repeatable and reliable, potentially, than our human raters. We did use three raters to try to increase our reliability and, you know, we, we sort of trained, uh, you know, to sort of be congruent and we still only got moderate agreement. So, uh, you know, I'd be very excited, and I think the, the folks who watched all the videos would be very excited to have a, a tool that was faster and better, uh than and again, that we could, you know, rely on scientifically.
Speaker 2:Love those answers. We've said the C4, but we're actually compiling them and going to be sharing them See. So, some cool research ideas and, for those of you just joining us, we're discussing how needle sharpness is minimally affected by vaccine vial puncture with our guests Rachel and Julia affected by vaccine vial puncture with our guests Rachel and Julia.
Speaker 3:Julia, as a veterinary student, how did your training and previous work not only help you to do the study design, get the work done, get the manuscript written like really cross the finish line. That's impressive, and how did your work, previous experiences, prepare you for that?
Speaker 5:Yeah, thank you. So as part of the veterinary medicine curriculum here at Midwestern University, we're enrolled in a course called Principles of Veterinary Scholarship, which is actually organized by Dr Kreisler, and the class is structured to enhance students' skills in creating scientific questions and solutions surrounding veterinary medicine, and so I specifically believe that it contributed to my ability to kind of assess scientific evidence when reviewing previous peer-reviewed literature, you know, for this project and just kind of going through a systematic approach on how to approach a problem.
Speaker 2:Very cool. I'm actually presenting at the SAVMA Symposium at Davis tomorrow morning, so excited to inspire students to get excited about scholarly publishing. This next set of questions is going to be very important for our listeners, and the first one deals with the veterinarian's perspective. So, rachel, what is one piece of information the veterinarian should know about? Needle sharpness and vaccine vial puncture.
Speaker 4:I would say the bottom line is it's okay not to change the needle if you use gentle vaccine vial puncture technique. Very well said.
Speaker 2:And on the other side of the relationship, Julia, what's one thing clients should know about this topic.
Speaker 5:I think they should know that, as veterinarians, we are regularly assessing optimal vaccination protocols that can contribute to environmental sustainability while reducing medical waste.
Speaker 3:But also ensuring that the welfare of our patients remain uncompromised. I wonder if they would even notice. Do you think they'd notice that we change needles or we don't change needles?
Speaker 4:I never did. I'm a second-career veterinarian so I had over 10 years as a sort of civilian pet owner and I will guarantee you I had no idea.
Speaker 3:Yeah, I don't think I would watch.
Speaker 4:I probably didn't.
Speaker 3:Yeah, I'm trying to think of like when my kids get vaccinated. Anyway, thank you guys again. Really fantastic and such practical information for our practitioners. We really appreciate it. As we wind down, we like to ask some fun facts. So, Julia, what is your favorite animal fact?
Speaker 5:My favorite animal fact is that sea otters use really hard shells or rocks to crack open their prey, such as sea urchins open their prey, such as sea urchins.
Speaker 3:Wow, interesting, did not know that. And, rachel, for you, what is the oldest or the most interesting item on your desk or in your desk drawer? If you have it, you can show it too.
Speaker 4:Oh, yeah, well. Okay, here we go. I have a prayer candle, so I have a prayer for useful data, right? That's too funny. Actually, it's a prayer candle useful data.
Speaker 2:Right, that's too funny. Actually, seeing your prayer candles, I saw on my vet school classmates Instagram story yesterday she had a prayer for paying off student loans, so you're not alone with some of our day-related prayer candles. And Julia love the aquatic animal. Fact. I have a very soft spot for sea otters, so they're awesome. Well, thank you so much, rachel and Julia. We really appreciate you being here today and sharing your research with us too.
Speaker 4:Great. Thank you so much for having us. Yeah, thank you for having us.
Speaker 2:And to our listeners. You can read Rachel and Julia's article in Jabma. I'm Sarah Ithlisa Fortier. Be on the lookout for next week's episode and don't forget to leave us a rating and review on Apple Podcasts or whatever platform you listen to.
