¶ Reptile Anesthesia Study
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 .
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 .
Yeah , our pleasure , thank you .
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 ?
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 .
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 .
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 .
You're stealing all my good one liners right .
We've been at this for too long . So , ashlyn , what were some important findings from this study ?
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 .
Can you just hear the person who first suggested that ? I told you that . But always good to have the evidence , absolutely .
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 .
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 ?
Yes , great question .
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 . 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 .
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 ?
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 .
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 .
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 .
Ashton , what inspired , you to get involved .
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 .
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 ?
Ashton , you want to go first ? I think you bet .
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 .
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 .
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 .
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 .
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 .
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 .
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 .
¶ Zoo Veterinary Training and Inspiration
Ashlyn , how did your advanced veterinary training prepare you to write this ? Manuscripts .
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 .
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 .
It is yes .
Yes , Alephia . How about you ? How did your advanced training prepare you to write this manuscripts ?
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 .
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 ?
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 .
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 .
And very important information for our clinicians . And then Olivia , what is one piece of information the client should know about sedation and reptiles ?
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 . 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 .
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 ?
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 .
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 .
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 .
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 ?
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 .
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 .
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 ?
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 .
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 ?
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 .
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 .
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 .
Absolutely . Thank you so much for having us .
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 .