Breaking Myths in Reptile Anesthesia

Discover the truth behind reptile anesthesia with our special guests Olivia Petritz and Ashlyn Heniff, who bring their expertise to Veterinary Vertex in a myth-shattering discussion. We examine a revolutionary study that challenges the long-held belief about administering sedatives in reptile hind limbs, focusing on the intriguing case of Eastern box turtles. Our conversation with Ashlyn unveils groundbreaking research on the effects of sedative protocols involving dexmedetomidine, ketamine, and midazolam, reshaping our understanding of hepatic first-pass metabolism in this species. Whether you're a vet, a pet owner, or simply a reptile enthusiast, this episode is a riveting exploration of the complexities and advancements in reptile anesthesia.

Our episode continues as we delve into Ashlyn's inspiring journey through the world of zoo medicine, where her research experiences have not only sharpened her expertise but also contributed to significant scientific advancements. Joining us as Olivia, who enriches the conversation with her transition from primary researcher to mentor, highlighting the joy of guiding passionate students like Ashlyn. We navigate through the intricacies of drug metabolism and the nuanced art of sedation in reptilian species, providing invaluable insights for professionals and caretakers alike. If you're fascinated by the diversity and specialization within the veterinary field, especially in zoo medicine, this episode is a must-listen, packed with knowledge and inspiration to fuel your passion for animal care.

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Transcript

Speaker 1: 0:00

You are listening to Veterinary Vertex, a podcast of the AVMA journals. In this episode we chat about four limb versus hind limb, administration of dex, metatomidine, catamine and eastern box turtles with Olivia Petrits and Ashlyn Heneff.

Speaker 2: 0:21

Welcome to Veterinary Vertex. I'm Editor-in-Chief Lisa Fortier, and I'm joined by Associate Editor Sarah Wright. Today we have Olivia and Ashlyn joining us. Olivia and Ashlyn, thank you so much for taking time out of the busy season to be with us here today. Thank you so much for having us.

Speaker 4: 0:37

Yeah, our pleasure, thank you.

Speaker 1: 0:40

All right, let's dive right in. Ashlyn, your article is a great myth buster. As a student or house officer, we're taught to avoid administering anything to reptiles in the hind limbs due to the renal portal system and hepatic first pass effect. Your study provides evidence to back up this claim. In one of my favorite reptiles, the eastern box turtle, as a student I participated in Matt Allender's wildlife epidemiology lab. So box turtle, everything. Can you give our listeners a bit of background on this study?

Speaker 3: 1:09

Absolutely so. At NC State we see a lot of eastern box turtles as both client owned pets and wildlife rehabilitation patients, and largely because of the fact that they can fully retract into their shells and box in hence their name we end up having to sedate a number of them in order to facilitate physical exams, diagnostics and treatments. And while we sedate them all the time, we realized no one had actually formally evaluated sedation or anesthetic protocols in this species or published on it. So we decided it was up to us to be the first. We also realized that, as you kind of touched on before, trainees and clinicians are routinely taught this idea that you can't give anything in the hind limbs to a reptile. But if you actually dig into the literature, there's very few evidence based studies to back this up. It's based on a lot of anecdotal evidence and it really just hasn't been studied that well. And furthermore, those studies suggest that there may be differences between species and different drugs.

Speaker 4: 2:15

And just another thing to add that in addition to the variability, species, the species, there's also some variability documented on where you inject, like hind limbs versus tail. So I think all of those things combined, we were really interested to evaluate it in this species.

Speaker 1: 2:33

To echo Lisa's prior comments on some other podcast episodes, it's always important to have evidence, not evidence based research. So, yeah, that's why I'm giving her credit for it, because I've heard her say it before.

Speaker 2: 2:46

You're stealing all my good one liners right.

Speaker 1: 2:50

We've been at this for too long. So, ashlyn, what were some important findings from this study?

Speaker 3: 2:57

Yes. So in our study we decided to look at three different sedative or anesthetic protocols. So the first was a combination of dexmenotomamine and ketamine in a four limb, intramuscularly, and then, for the second treatment, we took those same drugs but added medazolam and compared those two. Then, for our third group, we took the three drug protocol of dexmenotomamine, ketamine and medazolam and administered it into a hind limb in order to compare it to the effects we saw with the four limb injections. And what we found was, firstly, that four limb dexmenotomamine and ketamine alone resulted in clinically relevant anesthetic effects that were heightened with the addition of medazolam. And secondly, we found that hind limb rather than four limb administration of the three drug medazolam, dexmenotomamine, ketamine protocol resulted in reduced and more variable anesthetic effects, which is supportive of a potential hepatic first pass effect in eastern box, since all three of these drugs are primarily hepatically metabolized in studied species.

Speaker 2: 4:08

Can you just hear the person who first suggested that? I told you that. But always good to have the evidence, absolutely.

Speaker 4: 4:18

And I think there's like ketamine and dexamidotomine, have been used pretty commonly in a lot of different reptile species. But medavilim, I'd say, is a newer drug being used. It often is added on and not used solely, but there are several other papers looking at it as a sole sedative. I think the tricky thing is in larger reptiles which Eastern box turtles don't fall into that category, but large turtles and tortoises it often becomes a volume limiting drug. So I think a lot of these studies have looked at the addition of that drug in particular to kind of prove or disprove is it really effective? Does it really add some additional sedation effects that would justify its large volume? And we found that it did.

Speaker 2: 5:04

Yeah, very good. Very important paper, Ashlyn. There's so many things we don't know about reptiles in general. What sparked your research interest in reptile anesthesia?

Speaker 3: 5:15

Yes, great question.

Speaker 3: 5:17

So another mentor in addition to Olivia that I've worked with is Julie Boko, and she's a veterinary anesthesiologist who looks at advancing anesthesia and analgesia in non-domestic species, and I started working with her after my first year of vet school and I realized that was an area of research that I was really interested in as someone who wants to become a clinician working at a zoo.

Speaker 3: 5:40

There is so much room for growth in that area. Even though we have a lot of experience sedating and anesthetizing these zoo animals, the number of sedative and anesthetic events for each species is so small compared to what we have for dogs and cats, where we can retrospectively go back and easily find 1,000 dogs that have got the same protocol versus. You're not going to find 1,000 eastern box turtles unless you really go to every place that has eastern box turtles, and even then there's going to be variations in those protocols. So this is sort of an area that not only for turtles, I would also say for amphibians, for fish, for exotic mammals and birds. This is something I really want to advance as I go through my career.

Speaker 2: 6:27

That's great. What a great contribution. I can feel your enthusiasm. What a great yeah. You're just going to add so much to this literature into our profession. Thank you, olivia. What sparked your interest, and obviously sustained interest in reptile anesthesia?

Speaker 4: 6:42

Yeah, so I think I echo a lot of the things that Ashlyn said and I have collaborated with Julie Balco on many different sedation projects and a variety of species chickens, rabbits, now box turtles and I agree, I think it's disheartening at times to have these species that are very charismatic and either client owned or wild or housed at an institution like a zoo and not really have a lot of scientific evidence or something as basic as I just need to sedate it to collect X samples. So I think trying to investigate that further in a safe, studied, controlled environment to be able to apply that to some of those other species, and is really what inspired me to do this and continue to do that, and a lot of these clinical questions I think I'm interested in as well. Is it effective in the hind limbs versus not? We always say that it's not, but has there been any study done in this particular species? Well, no, and that's what prompted this study.

Speaker 2: 7:51

Yeah, there's so much we can do for the welfare of this broad category of zoo wildlife animals. I remember early on my residency so the very early 90s we'd gone to a zoo do an orthopedic procedure on a polar bear and they were giving it a gram academy every 10 minutes on the alarm beep, beep, beep, a gram academy. And I said why are you doing that? I said well, because we want to make sure it stays anesthetized to keep the people safe. And I was like, oh OK, what do your polar bears eventually succumb to? They're like liver disease. I'm like, huh, no kidding. So yeah, these things are really important and, to Ashton's point, difficult to do so. Given that difficulty, olivia, what inspired you to write this manuscript? This can't be easy to pull off. As Ashton was alluding to, dogs and cats are much more abundant and you don't have to unbox them to check the anesthetic protocol.

Speaker 4: 8:47

Yes, they're not really willing to comply with a lot of our requests often. So, yeah, I think we do have a turtle rescue team here at NC State. So they are wild box turtles and others. Box turtles are probably our most frequent fliers as far as that goes. But it's a rehabilitation that we do here. It's mainly student run, so we see a lot of box turtles that come through there. We also see them as pets on our clinical service here. So I think just the commonality of the species and the abundance in the area. So all of these turtles that we used were client owned and had appropriate consent forms and everything signed off. But yeah, I thought that if we had an adequate population size that this would be a reasonable, non-invasive study to do.

Speaker 2: 9:41

Ashton, what inspired, you to get involved.

Speaker 3: 9:45

Yeah, Olivia actually came up with the idea for this project first and she had been mentioning it to Julie Volko, and then they both mentioned it to me and I was immediately totally on board, partially because I knew it'd be a great mentorship team to work with and then also I had worked at the Turtle Rescue Team that was just mentioned. I had a lot of experience sedating wild turtles that came in and needed a fell, repair, needed blood collection or maybe even needed an amputation. I found subjectively that I felt like it was really hard for me to predict what I was going to see with the amount of each drug that I was giving, Like it did not seem to be super consistent between turtles, and I realized part of the reason is that we're doing this off of anecdotal evidence. We don't really have a lot of published data, so I thought we could do something to make it better for the next group of Turtle Team students.

Speaker 1: 10:45

Yeah, it's really important, especially just to build on future studies too. Thank you so much. Then, ashton and Olivia, if you want to answer this question together, you can. What was the most surprising finding from your manuscripts?

Speaker 4: 10:59

Ashton, you want to go first? I think you bet.

Speaker 3: 11:02

Yeah, I think we probably feel the same way. But so two things that go together. First, even though Heinlein administration did result in reduced efficacy, it was effective. Like all the turtles stopped ambulating, all of them experienced some degree of sedative effects. Then the most surprising thing for me that goes off of that is the fact that we saw very variable effects with the Heinlein protocol. Some of those turtles that got the Heinlein injections were very sedate, to the point that I would even call them lightly anesthetized as we could intubate them. In contrast, a couple of turtles that got those Heinlein injections were actually lifting their heads up and almost appearing to look around the room. Most of the turtles fell somewhere in between those two extremes after the Heinlein injections. This was in contrast to the four limb treatment groups, where the sedation scores for those groups were pretty consistent Among the turtles.

Speaker 4: 12:02

And I think, as we mentioned before, it is kind of lore that you should never inject a reptile of any species, all thousands of species of them in their hind limbs or tail. So this was in contrast to that finding or to that lore, but also, I think, helpful for the rare event that you may get a turtle, a box turtle, that has a bilateral four limb amputation or fractures or some other lesions or wounds that prevent you from injecting them in their four limbs. That a Heinlein would be a reasonable but variable option. Yeah, anything else, ashlyn.

Speaker 3: 12:41

Nope, I think that's about it. I think there's a lot more to go in terms of, you know, there's analgesics to look at, there's other anesthetics, and I think it's also important to consider, you know, how are these drugs metabolized? Is it hepatic metabolism or are they excreted renaly without any kind of bio transformation? And then you know, further complicating things is the fact that we're extrapolating from mammals. You know what we know about these drugs in mammals, but at least from you know this finding, with this Heinlein variability, and given the anesthetics that we gave are primarily hepatically metabolized in mammals, we're suspecting, you know, this is the result of a hepatic first-pass effect, which I think is a little bit in contrast to what the standard understanding is, that it's the renal portal system is why you shouldn't inject in the rear legs.

Speaker 4: 13:33

But this is, like Ashlyn said, most likely hepatic first-pass effect. So a little bit academic but still, I think, important for veterinarians to know.

Speaker 1: 13:43

I actually did look that up after I read your manuscript and I was like I always thought it was the renal portal system and I kept seeing that you're saying hepatic first-pass effect. So yeah, I learned something myself from reading your articles.

Speaker 3: 13:53

Well so did I until I took this project on. When I first started vet school, that was one of the first things I was taught was oh, the renal portal system. But yeah, if you actually dig into the literature, it's not quite so black and white.

Speaker 1: 14:07

Very interesting. I can see it's being useful too for species that have kind of scary front ends, like the alligator snapping turtle, or sometimes you can't always have forelimb access safely. So definitely. And to our listeners that are just joining us, we're discussing reptile sedation with Ashlyn Henev and Olivia Petrits. Ashlyn, how did your advanced veterinary training prepare you to write this? Manuscripts.

Speaker 3: 14:33

Yes, as I touched on before, I started doing research very on in veterinary school, at first with Julie Boko and then also with Olivia Petrits, Greg Blubart, lots of other awesome faculty at NC State. I initially started doing research because I knew I wanted to work in Zoom Medicine and everybody will tell you you should get some research experience. That's really important. But I quickly realized this was something I actually loved as much as the clinical side of things, if not more. I've taken on several first-author projects throughout vet school and each one has made me a better writer, better problem solver. Then, when I got to this study, even though I had never done a sedation or anesthesia study before, I had done several other studies, including euthanasia, coagulation, and those techniques and skill sets that I developed from those projects were really easily transferable to this one. I just keep taking on these opportunities in order to become a proficient scientist, not just to pad my resume, not just doing these projects to do it, but to have the opportunity to actually contribute to this field before even graduating from veterinary school.

Speaker 1: 15:51

I'm sure future advanced training programs will really appreciate that. You already know how to write and publish too. That's a good skill they have. This is nodding your head.

Speaker 3: 15:59

It is yes.

Speaker 1: 16:00

Yes, Alephia. How about you? How did your advanced training prepare you to write this manuscripts?

Speaker 4: 16:06

Yeah, I think I've been through residency internships myself and I would say doing research as a primary author versus a corresponding or mentor is a little bit different. I think that's something that I've worked pretty hard on these last few years and that's a big transition from you being the primary researcher to supporting others in research. It's very fulfilling and I love mentoring people. Ashlyn is just a gem. This was a very easy project because of her knowledge and experience.

Speaker 1: 16:43

Agree, it is different, being on the other side of things. There's a fellow at the Vancouver Aquarium where I did my fellowship and she's finishing a study that I had started when I was there and I was reviewing her abstract for her and I had to really look at it from a different lens, since I wasn't the one writing it right. I was kind of editing it for her and kind of looking to see what are the important key parts and communicating that in a way that's constructive and helpful. So I learned a lot through that experience. This next set of questions are really important for our listeners. Ashlyn, what is one piece of information the veterinarian should know before discussing the hepatic first pass effect in reptiles?

Speaker 3: 17:19

Great question. So, as we touched on a little bit, you know just distinguishing between the renal portal system and the hepatic portal system in reptiles. Their hepatic portal system is different from the mammalian one, so that's another layer of confusion if you're talking to clinicians. But basically making the point that it's not black and white, it's not going to work in the hind limbs, or never do it in the hind limbs, because some studies have actually found no difference between cranial and caudal injection sites. I mean you really need to think critically about the patient, the clinical presentation, the drug you're using and where you're giving it. While studies are pretty limited, some historical papers showed that more of the venous blood from the tail of a turtle species went to the kidneys While more from the hind limbs went to the liver. And while we have very limited prospective comparisons of this, I think it's just really important to take all factors into consideration when choosing your injection site and your protocol.

Speaker 4: 18:26

And I think knowing the metabolism of the drug, something that's a little bit more academic, right A lot of clinicians, myself included, you know we look at the side effects of the drug, the duration of drug, dose of drug and sometimes the actual metabolism of it. You know, either gets lost or forgotten along the way. So I think that is really important consideration as well.

Speaker 1: 18:48

And very important information for our clinicians. And then Olivia, what is one piece of information the client should know about sedation and reptiles?

Speaker 4: 18:56

Yeah, so I think one. It's different than their dog and cat getting sedated. I think the variability species to species is important to know and I think for the most part a lot of exotic and zoo clinicians are very forthcoming with that information. Like this is a very novel species and you know or I've never sedated the species before. So I think being having some degree of transparency is important.

Speaker 4: 19:22

But I also think it's important for clients to know that the duration of sedation and recovery is often much, much longer. So we kind of go with the verbiage that you know, reptiles do everything much slower. They get six slower, they get better slower, and that pertains to sedation and anesthesia too. So if your veterinarian is a little hesitant to sedate your box turtle at 3 pm in a business day, there is very good reason for that because the recovery is often very prolonged. But that's why we do these studies, to try to figure out how long is long and what that would look like for the average X species. But yeah, just knowing that it will take probably longer than a mammal, and that's something we like to do at the beginning of our business day rather than at the end.

Speaker 2: 20:10

Great advice. It's fascinating to me that our veterinary profession is amazing. We have so many cool options on things that we can do subspecialties, general practice, not just specialties, but species specialties, which doesn't happen in obviously anywhere in human medicine. So, Ashlyn, I'm just curious, what inspired you to pursue a career in zoo medicine?

Speaker 3: 20:35

Great question. So I sometimes make the joke that I knew this is what I wanted to do since conception, because I really cannot recall a time where this was not what I was meant to do. So I went to zoo camp as a kid. I was three years old and I told my parents I'm like I'm going to work there someday. And it never really changed.

Speaker 3: 20:58

But as I became an adult, I mean really interested in medicine. A lot of my family comes from a medical background and I love going to the zoo. Like if I could have gone to the zoo every day as a kid, I would have just absolutely loved it. And I specifically recall when I was 15, 15 years old, just like reading about the American College of Zoological Medicine and like, oh my gosh, you can pursue residency training to be a vet at a zoo. And I realized that sort of everything I've ever wanted to do kind of fit within that college. And here I am 11 years later and that's still really what I'm, what I'm trying to do.

Speaker 3: 21:34

And as far as, like you know, the kind of adult reasons for it, you know, not just being a kid who loved animals is that I'm really interested in, just the unique physiology and pathologies that affect these exotic species from around the world and finding ways to advance their standard of care. And also that I believe that zoo's and aquariums are integral to successful wildlife conservation. Because I really believe you know, with the state of the environment these days and you know human wildlife conflict and habitat degradation, that we really really need zoos, you know, to work with these species in close contact where we can learn a lot about them and you know potentially even breed them captivity to reintroduce them or even just breed them in captivity to learn more about them, in order to apply that to the saving species in the wild and to educate people about you. Know why we're doing it.

Speaker 2: 22:32

That's a really great response. You know, I think your passion for zoom medicine is the same as mine in equine. That can tell you never crossed my mind a single moment of any day in my 58 years of life to become a zoom medicine doctor. Olivia, how about you? What inspired you to follow the path to zoom medicine?

Speaker 4: 22:51

Yeah, mine is, maybe not as early on Schleswig's, my first passion was Dinosaurs. I wanted to be a paleontologist this was pre Jurassic Park and then I changed change mind in high school, decided to pursue veterinary medicine. I have no veterinarians in my family. First doctor in my family and my first job in undergrad was as a zookeeper at a small zoo and I really not entertain the idea of zoo or exotic species Really at all, just because I had not been exposed to it other than going to zoos. So I kind of thought my options were like large animal, small animal and that's all I knew.

Speaker 4: 23:35

But there was a part-time zoo, key part-time zoo vet. He was a general practitioner that came there and His name is Kurt Voli. He still is a zoo veterinarian, not at this particular zoo, but he was just. He was really inspiring, like he, the fact that he could come in and transition from a primate to a bird, to a Reptile and and he had, you know, no formal training in zoo medicine. But I was just amazed and thought that that seemed pretty interesting and there was never a dull day and every day was different, and so I thought why don't I when I try to do that? And that's what kind of Inspired this career, and I echo everything that that Ashlyn said about. You know, helping both animals in captivity as well as those in the wild and the human wildlife interactions and conservation medicine in general, I think is Something that we can each kind of work on as veterinarians, but I think zoo and wildlife vets Get to be maybe a little bit more on the forefront of that.

Speaker 2: 24:38

Well, thank you both. I've learned a lot from this conversation. As we wind down, we just asked a nice to ask a little bit more of a personal question. So, ashlyn, what is the first concert you attended?

Speaker 3: 24:50

Yes, so I'm from Indianapolis originally and the first concert I went to was on the lawn downtown Indianapolis death cab for cutie. I was about 10 years old and I was playing tag with my friends while my parents were actually enjoying the concert.

Speaker 2: 25:06

That's awesome. I I love you for you. I hear you're a puzzle aficionado. When you like to do puzzles, do you start from the outside and do the perimeter, or do you do like color or schematic pieces in the inside first?

Speaker 4: 25:25

So I typically start with the corners, just because that may be Easy as to start. Then I work my way around the edges, so then I fill in the middle. I'm not sure if that's the standard of what you're supposed to do, but there we are.

Speaker 2: 25:38

That's fascinating. We've gotten a lot of edge, but not specifically corners. Did people mess with you and like move your corner from top to like? That would be me. I'd move you from Two o'clock to eight o'clock and the next time you turn your back I'd move you from eight to ten.

Speaker 1: 25:55

Has been, has been known to hide a corner or two, which is very frustrating, but yes, Since we've been getting the edge answers so much I've almost been likening it to a physical exam. You know you start either like nose to tail or vice versa, and I feel like as doctors, that's our mindset, although not always the cases. We've learned from some recent episodes, but kind of interesting. So, and just thank you again, ashlyn and Olivia, we really appreciate your time today and your contribution to AJBR.

Speaker 3: 26:25

Absolutely. Thank you so much for having us.

Speaker 1: 26:27

Yeah, thank you. And to our listeners you can read Ashlyn and Olivia's open access AJBR article on our journals website. I'm Sarah Wright with Lisa 40a. You want to thank each of you for joining us on this episode of the veterinary vertex podcast. We love sharing cutting-edge veterinary research with you and we want to hear from you. Be sure to leave us a rating and review on Apple podcasts or whatever platform you listen to.