Veterinary Vertex

Vitamin E Deficiency in Horses

• AVMA Journals

Share episode

Send us a text

Could your horse be vitamin E deficient without you knowing it? New research suggests this vital nutrient deficiency might be far more common than we realize, even in horses with access to fresh pasture.

Drs. Amy Johnson and Megan Palmisano join Veterinary Vertex to discuss their groundbreaking study examining vitamin E concentrations in hospitalized horses. They share a stunning revelation: approximately 17% of adult horses and 5% of foals arrived at their hospital already deficient in vitamin E, despite coming from the nutrient-rich mid-Atlantic region. Most surprising, these deficiencies occurred across different management styles, suggesting this problem transcends typical risk factors.

As Dr. Johnson explains, vitamin E deficiency has serious implications, particularly for neurological health. Her work as a neurologist revealed connections between vitamin E deficiency and devastating conditions like equine motor neuron disease, equine neuroaxonal dystrophy, and equine degenerative myeloencephalopathy. The researchers initially hypothesized that hospitalization might worsen vitamin E status by restricting access to green forage, though their findings suggest short hospital stays don't significantly impact levels.

The conversation delves into practical aspects every horse owner should know: the importance of testing individual horses rather than assuming herd status, proper handling techniques for blood samples to prevent false readings, and recommendations for seasonal testing schedules. Perhaps most critically, they emphasize that horses at the same farm eating identical diets can have dramatically different vitamin E statuses.

For veterinarians and owners alike, this episode offers vital perspective on an often-overlooked aspect of equine nutrition that could prevent serious neurological disease. Understanding your horse's vitamin E status through regular testing and appropriate supplementation when needed provides a simple but potentially life-changing intervention for their long-term health.

Listen, share, and leave us a review to help more horse owners discover this essential information about equine vitamin E requirements!

Open access JAVMA article: https://doi.org/10.2460/javma.24.09.0590

INTERESTED IN SUBMITTING YOUR MANUSCRIPT TO JAVMA ® OR AJVR ® ?

JAVMA ® : https://avma.org/JAVMAAuthors

AJVR ® : https://avma.org/AJVRAuthors

FOLLOW US:

JAVMA ® :

Facebook: Journal of the American Veterinary Medical Association - JAVMA | Facebook

Instagram: JAVMA (@avma_javma) • Instagram photos and videos

Twitter: JAVMA (@AVMAJAVMA) / Twitter

AJVR ® :

Facebook: American Journal of Veterinary Research - AJVR | Facebook

Instagram: AJVR (@ajvroa) • Instagram photos and videos

Twitter: AJVR (@AJVROA) / Twitter

JAVMA ® and AJVR ® LinkedIn: https://linkedin.com/company/avma-journals

Wellness Pet Foods:

Mealtime is more than a bowl of food. It's the foundation for a long and healthy life. At Wellness, dry recipes are crafted with the highest quality natural ingredients for a taste that pets love and scientifically proven through AFCO feeding trials to ensure that every complete and balanced meal supports the five signs of wellbeing. With Wellness Pet Foods, pet parents can share a life of well-being together with their pet.

Sarah Wright:

This is Veterinary Vertex, a podcast of the AVMA Journals. In this episode we chat about vitamin E concentrations in hospitalized adult horses and foals with our guests Megan Palmisano and Amy Johnson.

Lisa Fortier:

Welcome to Veterinary Vertex. I'm Editor-in-Chief Lisa Fortier, and I'm joined by Associate Editor Sarah Wright. Today we have Megan and Amy joining us. Thank you, guys, so much for being here on Veterinary Vertex today and Amy for all the times I ask you about vitamin E in my own horse. I appreciate you.

Amy Johnson:

Thank you both for having us today.

Megan Palmisano:

Yeah, we're very pleased to be here.

Sarah Wright:

All right, let's trot on over. So, Amy, your JAVMA article discusses vitamin E concentrations in hospitalized adult horses and foals. Please share with our listeners the background on this article.

Amy Johnson:

So we know that vitamin E is a really essential vitamin or nutrient for horses.

Amy Johnson:

It provides antioxidant support to the body, but especially to the nervous system as well as the muscles, and deficiencies can adversely affect health.

Amy Johnson:

We also know that horses primarily get their vitamin E from green forage, so pasture turnout and good quality hay. When we have horses that are hospitalized, we often don't provide them with green pasture turnout and while we'd like to think we provide good quality hay in the hospital, sometimes we intentionally hold them off feed if they come in for an abdominal problem or something like that. So, we became interested in whether or not we were actually creating a vitamin E deficiency in these hospitalized horses when we were not providing them with pasture turnout and maybe holding them off feed for a period of time during their hospitalization. We know that that does occur in hospitalized people that they're not provided with food sources that are rich in vitamin E. During hospitalization, and even within a couple of days, they can develop deficiencies. The effect of this overall on their recovery and prognosis isn't clear, but we were concerned that we might be setting these horses up for future problems and if we needed to supplement them during hospitalization, we wanted to know that.

Sarah Wright:

Super cool research question and really cool study as well, so thank you for sharing it with us.

Sarah Wright:

So, Megan, what are some of the important take-home messages from this JAVMA article?

Megan Palmisano:

Yeah, so I think that there's a few important take-homes from this article. I think the first is that vitamin E deficiency is prevalent in horses. So, even without thinking about hospitalization, this study was performed in a pretty vitamin-rich area. We were in the mid-Atlantic, where most of our patients were coming from, and we found that there is like almost 17% of those adult horses that presented on emergency were deficient and about 5% of the foals that presented were deficient.

Megan Palmisano:

So I think that's one of the big take-homes, and I think second was that obviously the goal of the study was looking at how hospitalization potentially impacted the vitamin E concentrations in these horses and so, over that approximate like week-long stay that we saw in the patient population, it did not appear that there was any significant decline in vitamin E. But I think this also highlights a lot that we don't know about vitamin E, because obviously there are bodily stores of vitamin E in multiple different organs, and so is it something that they're doing a good job of regulating while they're not provided these sources. It's definitely something that we don't necessarily know.

Lisa Fortier:

It's highly, highly under-acknowledged in the general equine population for sure. And Amy, I know you know for a long time you've been interested in vitamin E. I'm interested in a couple things. What initiated that? I'm going to guess it was one person and one disease. And second, you said we had this question. How did that question come up? Like, how is this different? What are we doing in the hospital? Like I'm just curious. What sparked that question?

Amy Johnson:

Sure, so I mean vitamin E in general. I, as you know, I'm a neurologist and I learned from Sandy De La Hanta at Cornell and Tom Divers and Husni Mohamed, and they were all very instrumental in discovering this neuromuscular disease equine motor neuron disease that is very strongly linked to vitamin E deficiency in adult horses. And the interesting thing to me about the evolution of this is that we saw a number of cases when I was up at Cornell. I don't really want to date myself, but we'll say I don't do that.

Lisa Fortier:

I just said a long time I didn't date you.

Amy Johnson:

And then when I came down here to Pennsylvania to start working, I felt like we weren't seeing a lot of vitamin E associated disorders and I attributed that to better commercial diets and supplements.

Amy Johnson:

And the weather down here is a little bit more temperate than the weather in Ithaca, so maybe the pastures are a bit better, maybe the hay quality is different, and I really, for a period of time, was not diagnosing very many diseases associated with vitamin E deficiency.

Amy Johnson:

But then things seemed to change and whether it was just that we weren't looking for the deficiency before or the incidence has increased is a little bit unclear to me.

Amy Johnson:

But certainly as we started looking, we were recognizing horses with neurodegenerative diseases that have a strong association with vitamin E deficiency. So these are things like equine neuroaxonal dystrophy and equine degenerative myeloencephalopathy. These are conditions where the brain and the spinal cord are having these neurons that are dying for slightly unclear reasons, which is beyond the scope of probably this podcast. But we know for those diseases that vitamin E is a risk factor and we started checking more often horses in this area and recognizing that, despite my perception of really excellent management of these horses and pasture exposure and turnout that we were catching, some that were deficient in vitamin E, which made us measure more and more of them, and so I'm realizing, as time goes on, that this actually still is a problem for our equine population. It's something that we need to be concerned about, it's something that we need to address, and hopefully that will allow us to reduce the incidence of these neurodegenerative diseases that can be so devastating for horses and their connections.

Lisa Fortier:

And the second part of that question, Amy, was what really made you think huh, I wonder what's happening in the hospital.

Amy Johnson:

Really some discussions with Carrie Finnell, actually at UC Davis, who's also very interested in vitamin E and has done some work in vitamin E dynamics, and I realized how quickly levels can change in an individual animal. They can increase very quickly with supplementation and they can also decrease fairly quickly if it's not provided to horses. I mean, obviously they do maintain some body stores, but it seems like more labile than I might have predicted before. I started reading more literature about this and again, we understand that vitamin E deficiency is a risk factor, but we don't necessarily know when in the horse's life this deficiency is occurring and why it's occurring. So sometimes we have horses that have a history of being born or raised in areas where they didn't get pasture turnout, and those cases are easy.

Amy Johnson:

But we hypothesize that for some horses maybe the deficiency isn't because of the way that they're managed at home. Maybe they did have some critical illness that caused a lot of oxidative stress to their body and so they were actually using up all of their antioxidant stores and they had a higher. You know, they might have a higher body requirement for vitamin E, and so in a referral hospital like where we work, we see some of the sickest horses that probably have the most critical illnesses and the most oxidative stress, and I worry that maybe we were setting these horses up for future problems if we weren't addressing a vitamin E deficiency while they were in the hospital, either because they weren't getting enough vitamin E in the diet that we were providing to them during hospitalization, or they were using up their antioxidant capacity fighting their disease.

Lisa Fortier:

Yeah, very elegant study, Megan. Earlier, Sarah and you had a little discussion about what were some of the most important findings, and always when we do these studies we find something that really surprised us. What are one or two things that really surprised you and Amy in this article?

Megan Palmisano:

Yeah, so I think one of the things that surprised us the most was actually the main findings of this study. I think we both had anticipated that, even over an average duration of hospitalization, so if we're thinking somewhere between five and seven days that we would see significant declines in vitamin E in this population Because, as Amy had spoken about earlier, in humans there's actually a lot of, there's a lot more literature out there about vitamin E and its importance in critical illness. So humans that are being presented to the emergency room or are potentially on ventilators, those patients are actually found to be significantly deficient in this important micronutrient, and so I think that that was the first surprising finding is that we did not find this significant decline in vitamin E. I will say our patient population. There definitely was a lot of horses who were on vitamin E, so I think some of those horses who were in hospital for longer, as Amy said, it's definitely becoming a more popular finding, and so I think in some of those cases we were supplementing horses because obviously it has so many beneficial properties. So, I think that that definitely could have also played into that.

Megan Palmisano:

And then another thing that was sort of interesting that we don't really have a great answer for yet was when we were looking at the foal population and so, looking at those foals that presented, there was a number of them that were deficient on admission, but we actually found that there was an inverse correlation between the vitamin E concentrations in these foals and whether or not they had failure of transfer, of passive immunity, which I think is really really odd and interesting, and I don't have really a great understanding as to why this is. We had hypothesized maybe this had to do with our really proactive referring veterinarians in the area and that we don't know the components of plasma that's administered. And so if they're seeing a foal before referring to a hospital and they have these concerns, maybe they provided plasma to these foals and maybe that was something that influenced their vitamin E status. But I think that this is definitely something that just shows there's a lot we we don't know about this important nutrient.

Sarah Wright:

They definitely teed me up well for our next question here, Megan, as far as what are the next steps of future research? Sounds like there's a lot of hypotheses, a lot of great research questions, so what are you going to do next?

Megan Palmisano:

Yeah, so so.

Megan Palmisano:

Yeah, so I do think that there's a lot of different avenues that can be investigated with vitamin E. I think one of the ones that Amy and I have talked about is obviously the area we performed this study was an area that is actually not deemed to be too deficient in vitamin E, and so I think one of the things that we would be interested in looking at further is investigating vitamin E concentrations in areas of the country that are known to be more deficient, so areas that have less green pastures, more desert areas or arid areas.

Megan Palmisano:

I think that's possibly one area to explore, and then I think another, another big area is the importance in these vitamin E concentrations in the foal population. So, as you said, Carrie Finno has done a lot of work investigating this area, in particular, with specific neurologic diseases that we have examined in horses, but I think that there's a lot we don't know about. When is this critical period and what is the insult that ultimately might play a factor in development of these diseases as well. And so, and I think metabolism is a big area that needs further investigation as well Just how the body, how the bodily stores of vitamin E, how horses are able to one kind of mobilize those stores. And two, whether or not actual metabolism plays a role in any of these horses that are deficient.

Sarah Wright:

Well, it sounds like there's a lot of future research that you have on your plate, so we look forward to hopefully receiving some more manuscripts from you. So, AI is definitely a very hot topic. We're hearing about it in all different sorts of avenues and fields in the world, but specifically for this research topic, do you see a role for AI in this area of research Amy?

Amy Johnson:

I mean, the short answer is yes. Am I going to lead the AI charge? Maybe not, but I think that AI is much better at handling really large data sets than I am, and so, of course, we did research during one season at one hospital in one area of the country with a relatively small number of patients compared to some of the huge human studies on topics like this. So, it would be really nice to use some kind of AI technology I'm going to leave it loose that can kind of accumulate the data.

Amy Johnson:

There are several different labs in the United States that are routinely measuring vitamin E concentrations and probably have the data for the signalment of the horse and the area of the country where the sample is coming from and to process that information and look for trends. So are there differences between different regions of the country? Are there differences between seasons? In the winter, when horses don't have access to pasture as much, or at least the grass isn't growing, do they need supplementation during the winter but not during the summer, and does that change depending on where the horse is housed? Are there certain breeds that are much more likely to have a low vitamin E level and should be supplemented? I think that, again, acquiring one of these kind of massive data sets and then having a computer look for the trends will provide us with a lot of information that would be simply impossible for me to do with a spreadsheet on my computer.

Sarah Wright:

Yeah, I think it's a pretty common theme throughout veterinary medicine, no matter what species you work with. As always, we sometimes have low sample sizes, so definitely be super interesting. And for those of you just joining us, we're discussing vitamin E concentrations and hospitalized adult horses and foals with our guests Megan and Amy.

Lisa Fortier:

Megan, how did your training or previous work help you to design the study, complete it and then write this article?

Megan Palmisano:

Yeah, so I mean, I'm still pretty early on in my career, so I was really fortunate to have the mentorship during my residency that has really helped me with projects like this. So I know I had spoken with Amy about wanting to get involved in this project and together we were able to modify the study to try and get the most information out of it. So that's where we started adding in foals that we're presenting to the hospital as well. So I think a big thing for me is just having the mentorship that I had during my residency. But any previous research experience that I've had throughout my internship and throughout my residency has all helped a lot.

Sarah Wright:

So just exploring the literature and getting that exposure- Now, this next set of questions is going to be very important for our listeners, and the first one is going to deal from the veterinarian's perspective. So, Megan, what is one piece of information the veterinarian should know about vitamin E concentrations in hospitalized adult horses and foals?

Megan Palmisano:

Yeah, so I think the big one is that, although we ultimately did not find any significant decline in vitamin E concentrations in those hospitalized horses, I do think that vitamin E can still be a really beneficial supplement, especially in these hospitalized patients that we have concern for neurologic or neuromuscular disease or potentially have any sort of ongoing oxidative damage, since we do know it is a really potent antioxidant.

Sarah Wright:

Very well said. And Amy on the other side of the relationship, what's one thing clients should know about this topic?

Amy Johnson:

To me, the most important kind of result of this study was that 17% of the adults came in with a deficiency, in an area where deficiency is not thought to be that common, and so I think it's really important for clients not to assume that their horse has an adequate vitamin E status and they need to test the individual horse. We haven't mentioned this before, but it's not unusual that we have multiple horses at the same farm and some of them have adequate status and some of them are low, so you can't generalize and just test one horse in a barn and then assume everybody's doing okay. It's really important to test the individual horse and not assume that they have adequate status, because, although it costs money, supplementation is pretty easy and it's well accepted by most horses, and you may be saving yourself a lot of heartache down the line if you can prevent some of these problems from developing.

Lisa Fortier:

Well, we're on the topic of testing. Amy, how often do you recommend that people test their horses for vitamin E levels?

Amy Johnson:

So, I think that once a year testing if the horse is normal is probably adequate, although I've dabbled in the idea of whether we need to do seasonal testing and test them once during pasture turnout in the summer and then once again in the winter when they're eating more of a hay-based diet, and certainly if the horse is on the low end of normal and not being supplemented in the summer. You know, if they have kind of borderline adequate status, I would either supplement that horse throughout the winter or I would check again to make sure that that horse isn't dropping into what we consider an inadequate level during the winter months. Assuming you're in an area that has a summer and a winter.

Lisa Fortier:

Well, you know where I am in Ithaca. I've started wrapping it into a twice-a-year glucose test as well, just to get a baseline on where my metabolic fat horse is, or anybody in the barn. So, thank you for that advice.

Amy Johnson:

Yeah, that makes sense.

Lisa Fortier:

Amy there's a couple other tips and tricks for veterinarians when they're drawing blood on how to make sure that it's stable and to decrease false levels of vitamin E. Can you remind the listeners of those tips and tricks that you know about that? We might have forgotten.

Amy Johnson:

Yeah absolutely so. We usually collect our sample into a red top or a no additive tube, and there are a couple of important things about handling the sample. The first is to make sure that the blood doesn't sit on the stopper. So, you don't want to invert the sample and balance it on the stopper, because it will actually leach or bind vitamin E that's in the sample and it can falsely decrease the measured vitamin E concentration. The other thing is that natural light will do the same thing, so you wouldn't want to leave a tube you know in the cup holder of your truck in the sunlight after pulling it. Ideally it is kept out of light and it's placed into a refrigerator shortly after collection. And if you have a severely hemolyzed sample, you should probably draw that one again rather than submit a hemolyzed sample.

Lisa Fortier:

Who would store something in the cup holder in their truck, guilty as charged? Thank you for those reminder tips. As we start to wrap up a little bit, we like to ask a more fun question. So, we'll ask Megan first, and then Amy to follow If you could have a superpower, what would it be and why?

Megan Palmisano:

I think I'd go with the ability to teleport. I think that would make my day-to-day life much easier and also would make it really convenient to just kind of go wherever I would like to go.

Lisa Fortier:

Sure would have helped me yesterday in the snowstorm in Ithaca. Amy remembers those drivers well. You're like, literally we were going so slow and I drive a great big pickup truck, as you might imagine, right, and so we're going so slow on the roads it doesn't even register mile per hour on my speedometer and everybody's driving with their flashing lights in the daylight. I'm like, so I could have used a teleport yesterday. How about you, Amy, miss those days?

Amy Johnson:

Yeah, it was the snow plows spinning around and reversing in front of me that always made me worried in Ithaca. But I'm kind of annoyed, Megan, because you stole mine. That was the superpower that I was going to say is teleportation 100%. I have three kids and they're doing approximately a bajillion sports that all occur at the same time in different locations, and I could really use those powers at this stage of my life.

Lisa Fortier:

Yeah, that's a busy stage. I actually took chalkboard paint and painted an entire door in my pantry so everybody knew where everybody was going, they knew what meals were coming, because you can't do it every day. It just consumes way too much time to make that planning every day. So I feel you, I remember those days.

Sarah Wright:

So it's actually in the 50s in Chicago here today and we're like it's like spring what's happening. So I'll take it while it lasts, but thank you so much, Megan and Amy, for being here today and for sharing information about your article with our listeners.

Amy Johnson:

Thank you so much for having us.

Sarah Wright:

And to our listeners. You can read Megan and Amy's article in JAVMA. I'm Sarah Wright with Lisa 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.

People on this episode

Head Shot

Lisa Fortier, DVM, PhD, DACVS

Co-host
Head Shot

Sarah Wright, DVM

Co-host