Veterinary Vertex

Rethinking Equine Anesthesia: The Impact of Fasting on Postoperative Care

September 06, 2024 • AVMA Journals

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Ready to revolutionize your understanding of equine anesthesia? Join us as we challenge conventional practices with groundbreaking insights from Drs. Charlie Barton and Rachel Hector. Discover how their controlled randomized trial reveals that fasting horses before surgery doesn't offer the anesthetic benefits we've long believed. Instead, it delays postoperative manure output, causing unnecessary stress on our equine patients.

Tune in to explore the innovative advancements in equine anesthesia with Charlie and Rachel. We dive deep into their research, discuss the future steps for further studies, and reflect on the potential impacts on equine veterinary care. Don't miss this chance to gain cutting-edge knowledge and share your thoughts with us—let's reshape the way we approach equine anesthesia and postoperative care together!

JAVMA article: https://doi.org/10.2460/javma.24.04.0235

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Speaker 1:

You're listening to Veterinary Vertex, a podcast of the AVMA Journals. In this episode we chat about fasting horses perioperatively and how that decreases manure production and increases time to manure output postoperatively, which is a controlled randomized trial that was submitted by our guests Charlie Barton and Rachel Hector. Charlie and Rachel, thank you so much for being here today.

Speaker 2:

Thank you for having us. Yes, thank you for having us today. Thank you for having us. Yes, thank you for having us.

Speaker 1:

So, charlie, your Javma article discusses how fasting horses perioperatively decreases manure production and increases time to manure output post-operatively. Please share with our listeners the background on this study.

Speaker 3:

Yeah, so post-anesthetic colic is one of the most common complications that can happen after anesthesia. So we wanted to try and look at a way that we can maybe minimize this as a complication. Normally people will fast horses and historically that's kind of been the norm. People think that it maybe reduces the amount of intra-anesthetic complications, so it might improve the hypertension or the perfusional ventilation because they don't have that big heavy colon pushing against the diaphragm. But now we know quite a bit about gastrointestinal motility and we know that actually all these drugs that we use for anesthesia are going to slow down the GI motility and then fasting horses itself slows down the motility and it can also reduce their water intake as well as kind of change the gastric ph. So we know that there's actually quite a lot of detrimental effects of fasting horses and so we wanted to do a study where we could look at those intra-anesthetic complications as well as the post-anesthetic complications as well, the manual output and the colic incidents, and see if truly fasting horses is the best way to go about doing this.

Speaker 1:

Sounds like a really clinically applicable article, so thank you so much for sharing it with Javma. So, charlie, what are some of the important take-home?

Speaker 3:

messages. So we found that in our population there was no anesthetic benefit to fasting horses. So whenever we compared the fasted groups and the non-fasted groups, they both had very similar intra-anesthetic outcomes. Whenever we looked at ventilation, perfusion and hypertension, and then whenever we looked at the post-anesthetic uh passing manure and colic incidents, we found that the horses that had um had access to food, actually passed quite a bit more manure than those who hadn't, and they also passed manure more quickly. So all of these are risk factors for the development of colic. So not only did we find that actually there was no benefit with anesthesia, we found that actually there was a benefit to allowing them to eat food after surgery.

Speaker 1:

Yeah, super interesting. So looking forward to maybe other studies too, similar to this in other species. So, rachel, what sparked your research interest in post-operative feeding regimens?

Speaker 2:

So this is actually a project that I kind of wanted to do since my residency in anesthesia, which was now several years ago, mostly because I kind of looked at it from a welfare perspective, so an equine welfare perspective. You know. We bring these horses into a novel environment preoperatively. We put them in a stall, they're stressed, they're nervous, they're painful potentially, depending on what the surgical procedure is, and then the first thing we do is 10 to 12 hours before surgery, or maybe even longer if the day's really busy they get a muzzle, they get their food taken away, they're in a barn with other horses who are being fed and that just escalates sort of the stress and discomfort of the whole surgical anesthetic experience. And I feel like anesthesia should be about making maybe a negative experience as positive as possible.

Speaker 2:

So I kind of had this question for a little while and was reaching out to some of the surgeons to see if this was something that anyone would be interested in looking at. Cause it it took a bit of buy-in from the whole group to say let's try this study and standardize everything and separate these horses into groups and see what happens. And so thankfully we got very good buy-in from our team and everyone participated. Um, and yeah, really, I just wanted to know like is this thing? That's very stressful and uncomfortable for horses being withheld from feed and then subsequently withheld from feed after a surgical procedure. Is that really necessary? Like, do they do better and turns out they don't.

Speaker 1:

So yeah, thank you for explaining our thought process behind the question. That kind of started this whole study, because I think it is so important and so clinically applicable, as I said before. So you talked about the most interesting findings, the biggest take-home messages, but what was the most surprising finding from this article? Something you found that was like huh, didn't expect that.

Speaker 3:

So I think the most surprising finding we found was definitely about the effect of the muzzle. So we split our faster group into two, so we had one group that didn't have a muzzle on and one group that had a muzzle on and we really thought that having a muzzle on was going to reduce their water intake and then maybe have an effect on the amount of manure they passed as well. But we found that it really didn't. And just from like observation we didn't notice that horses that had muzzles on tend to be more stressed in their store and like were pacing and that type of thing a little bit more. But and nothing that we could look at statistically to say that there was a difference between the two groups and we did think it would at least affect the amount of water these horses drank yeah, super interesting.

Speaker 1:

Thanks for sharing. So, rachel, what are the next steps for research in equine postoperative teaching regimens?

Speaker 2:

So, at least from a perspective of our hospital, we stopped fasting our horses before general anesthesia for elective procedures about a year ago now when we compiled the data from this study.

Speaker 2:

So in another year we hope to go back and do a retrospective study of our population to compare to our previous colic numbers. We have a study that was performed here several years ago looking at the incidence of post-anesthetic colic in elective cases, so we have information about how many of our horses were expected to colic before we made this change. Now that we've made this change we have observed at least that the number of horses that colic post-surgery is extremely minimal. It used to be that every week at least one or two horses was getting treated for GI dysfunction post-anesthesia, so they were getting an azoogastric tube with fluids, they were maybe being rectal exams repeated and kind of were a little bit being watched more carefully because they weren't passing manure after surgery or they were actively colicking. And now, just observing our numbers, our population, that's much, much more infrequent. So we'd like to go ahead and get a retrospective study done after since we've done made these changes to the feeding and really truly quantify our colic proportion.

Speaker 1:

That's great and we hope to see that work in Javma maybe someday. So, rachel, do you see a role for AI in this area of research?

Speaker 2:

So I'm probably like the worst person to answer this question because I know so little about AI. I mean, this was the question that we maybe struggled with the most, I think you know.

Speaker 2:

from my very limited experience with AI, I could say like, potentially AI would help with looking at sort of large hospitals if they have this data or these data like about how much manure their horses have passed post-operatively, potentially kind of compiling that into multicenter studies about post-anesthetic GI complications in horses. But other than that, I'm really not an expert in that field by any means.

Speaker 1:

Yeah it's a tricky question, and we've, like, had other people on the podcast talking about, like small animal IV, catheter complications and all sorts of things, and the answers that some people have, though, are quite interesting as far as, like AI, maybe helping at least with like data analysis, more so, or even collection.

Speaker 2:

so we'll see maybe large data sets. It would maybe help some poor resident not have to compile quite as much information, but unfortunately there is not any AI that is going to go into a stall and collect manure and weigh it.

Speaker 3:

That's the resident's job that's the resident's job.

Speaker 1:

I was gonna say that sounds like a trainee. Definitely I have. I mean, I've been in those shoes before too eager student, student, uh, sign me up. So, and for those of you just joining us, we're discussing fasting courses perioperatively, and how it decreases manure production and increases time to manure output post-operatively, with our guests Charlie Barton and Rachel Hector. So, charlie, how did your training prepare you to write this article?

Speaker 3:

Yeah.

Speaker 3:

So I've been really lucky to be trained by a really great faculty and they're both incredible surgeons and also researchers.

Speaker 3:

So throughout residency there's been a really strong focus on evidence-based practice, so not only keeping up to date with the literature, but being able to read a paper and critically evaluate it and so understand, like any of the flaws and the limitations of the paper and the study design that they use and so that we can then apply the conclusions. So having this background was really helpful whenever I started writing writing this paper, so you can kind of critically evaluate your own work and read through your paper and think, okay, does this make sense, is this well written, is it easy to follow, and have I discussed the limitations of a study? So people who are reading it kind of know the potential flaws and then whenever they're looking at the conclusions, they can apply that and incorporate into their own practice. So ultimately as well, I feel like striving for the best for our patients and learning more about how we can improve patient care and optimize outcomes was emphasized throughout my training, and so I was really excited about this project and how impactful it could potentially be.

Speaker 1:

That's great. It sounds like it really aligned well with your goals.

Speaker 3:

Yeah, it did. It was a really cool project to be a part of and even better that the findings have been so impactful and kind of changed everything that we've done in the hospital with feeding these horses truly changed everything, like absolutely everything completely it's incredible to see those direct impacts.

Speaker 1:

not many people get to say that. Some people like, oh yeah, down the road it could lead to this if more people look at you know x, but for you it basically results in an immediate change.

Speaker 2:

It sounds like yeah as soon as we finalized the data collection. It was so obvious, the results were so clear that we made a hospital wide policy changes.

Speaker 1:

Very cool. Now this next set of questions is going to be very important for our listeners. Rachel, what is one piece of information the veterinarian should know about? Equine perioperative feeding regimens and their effect on anesthetic complications, manure output and colic proportion?

Speaker 2:

I would say this is there's so much to know, but I would say maybe like a key point for me is that happy horses are horses that have access to food and those horses do very well under anesthesia and they do better post-operatively and the post-operative complications are less.

Speaker 1:

Very well said, all right. So now I move on to the more fun portion of the podcast get to know you a little bit better. So, charlie and Rachel, when you start a puzzle, do you start with the middle pieces or do you do the exterior pieces first?

Speaker 3:

It has to be the outside.

Speaker 2:

Yeah, it's 100% the edge. I don't know who starts in the middle, but those people need to reevaluate their life choices.

Speaker 1:

I did peg you guys actually for border people just because of your. You said you really like following rules and instructions and to me that seems like almost a proper way to start a puzzle than filling rest in. Yeah, so love that Well, just thank you both so much, charlie and Rachel. It's been super fun having you on the podcast today and we're super, super excited that you shared this manuscript with Javma. It's so clinically applicable and it is going to change, hopefully, the way that people view equine anesthesia.

Speaker 3:

That's what we hope. Thank you so much for having us on the podcast. It's been really fun to record with you guys this morning. Yes, thank you very much.

Speaker 1:

Well, thank you both again, and to our listeners. You can read Charlie and Rachel's article and print Javma or using your favorite search engine. I'm Sarah Wright and I want to thank each of you for joining me 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 info, podcasts or whatever platform you listen to.