Skip to main content

Dr. William Bernard: Healthy as a horse: Probiotics and equine performance

December 3, 2018

Now that we understand the link between gut health and equine performance, there are several factors to consider when selecting a probiotic for your horses. 

The following is an edited transcript of Nicole Erwin's interview with Dr. William Bernard. Click below to hear the full interview. 

Nicole:         Certain supplements may have a legitimate place in addressing optimal performance in breeding in elite equine athletes. As an equine nutritionist and veterinarian, Dr. William Bernard is here to help provide a bit of perspective on how to identify and utilize the proper products in a multibillion-dollar industry. Dr. Bernard, hello.


William:         Hello, how are you?


Nicole:         Doing okay. Thanks for joining us. When I think about the history of horses in Kentucky, I imagine the sheer number that have made their way onto TV screens across the globe during The Kentucky Derby and other races. How do the stakes change when you're addressing the health of an animal that can have so much invested in its success?


William:         Well, I suppose I could say the stakes change because of the potential monetary value of that performance — if it's a race or a three-day event — or in the value of the animal that is a high performer. So, nutrition and supplements do have a place, and my major interest in that area, currently, is probiotics.


Nicole:         Well, how would you say that the daily demands of an equine athlete compare to, say, a hobby horse, and how would those translate into the nutritional needs to balance the optimal performance and health of that horse?


William:         A hobby horse is going to be nutritionally satisfied by a minimal pasture grass, good hay and, potentially, a little supplementation of a concentrate, such as grains. A performance horse is going to be using a lot more energy, so it's going to need a much higher level of nutrition, although we do have to be somewhat careful in that too high a level [of] nutrition can be harmful metabolically.


                    And then, I think also it's hard for us to realize or difficult for us to see, but the performance horse is under a lot more stress than the hobby horse. The hobby horse may spend a week outside, come in on Sundays, be ridden a little bit or not ridden at all, brushed off and taken care of, but doesn't have that daily stress of, say, a racehorse going out to the racetrack daily and exercising. There may be something new in the environment, there may be a new horse in the barn, and there's also a lot of shipping involved when you get to that level of performance. A performance horse may spend three or four hours in a trailer. It may have to get into an airplane. So, there is not only a caloric nutritional need for the performing athlete, but the consideration of the stressful periods that they actually go through.


Nicole:         There is a lot more attention on the gut response to some of those stressors that you're mentioning. Most animals have their own unique bacterial environment in the gut. Can you talk a bit about challenges in balancing bacteria in horses?


William:         Yes. If you think about one of the simplest things that probably alters that flora — which we can call the microbiota or the microbiome, which is the term that's used now to describe the flora of the gastrointestinal tract — the way we feed horses is totally different than the way they developed. The horse developed as a grazing animal; it spent the majority of the day grazing on grass — and, oftentimes, not that great quality of grass. Nowadays, we feed high-quality hay because they need the energy and we feed supplements, concentrates and grain, which are also high in soluble carbohydrates. And, yes, they provide a large amount of energy. However, we feed them in meals. The horse is a grazing animal. It's not used to being fed large meals of 10-12 pounds of grain. So that's one of the things that occurs, is that we initially stress the horse with the way we feed them.


                    And then, as we were talking about a few minutes ago, the stresses of their daily activities, the stresses of the social environment or lack of social environment, the stresses of being inside most of the day, the stresses of their performance, their stresses of travel, et cetera, can really influence the gastrointestinal tract. There have been some very interesting recent studies that have showed how stress can actually change the flora within minutes or within hours of that stressor.


                    Part of the aspect of probiotics and the microbiome that has become very interesting is the testing. When a new test comes out in some field, all of a sudden, we discover new things when we're able to look differently, look further, look in different places.


                    Relatively recently, RNA sequencing has become a technique where a scientist, veterinarian or biologist can take a sample of the flora of the gastrointestinal tract and do what's called the RNA sequencing — some people call it “shotgun RNA” — and can determine all of the different species and the number of those species of bacteria in that sample.


                    The reason that's such a huge advancement is that, in the past, we took that sample and had to culture the bacteria, which is not an exact science. Each bacterium has its own growth characteristics, and you can imagine the thousands of cultures you'd have to do on one sample to try to determine what it is. The new technique has allowed us to look at the population of bacteria in the gastrointestinal tract over time.


                    Studies have shown that, if you have a group of pigs and you look at their microflora with this sequencing of RNA, and then you stress those pigs and take another sample — you stress them by moving them from one pen to another or changing something predominantly in their life — you've changed the bacteria.


                    That also reflects on how we study these bacteria. If we're going to study these bacteria, we have to remember that, if we stress the animal before our study or during our study, we better watch where we take our samples or when we take our samples.


Nicole:         It seems like that would be kind of challenging in creating a meal plan for a specific horse, if the microbiome can change so quickly and be so different than the horse that's in the stall next to him. How do you determine feeding rates, what kind of feed, what probiotics to use? What has the research revealed that is working best, I guess, across the board?


William:         I think there's a lot of research on how to feed horses. That has been studied extensively because there is a financial reason to do so, not only for the feed companies but for the owners of the athletes themselves. Nutritionally, that has been researched and that information is definitely available.


                    Now, in the last 10 to 15 years, we've increased the amount of fat we feed horses. The thing to remember is, if you do make changes in the diet, you're going to need to make them gradually. If you make a sudden change to the diet, you're going to have a major impact on the gastrointestinal flora. If you make more of a gradual change to the diet, you're going to give it more time to adapt.


                    To get away from meal-feeding if possible, to extend that period of which we feed our concentrates, the trouble is that the management of that is very difficult. So, part of the way we manage the daily activities of these horses is going to dictate how we feed them.


Nicole:         What are some of the challenges in determining what probiotics you can use?


William:         That's a really good question — and a very important question [that] has not really been addressed in the past: What kind of probiotics should you be looking for? What are the factors that tell you this is a good probiotic? There are three or four very important things. One, and probably one of the most important, is species specificity. That means that, if you're going to use a probiotic for a horse, it should be a bacterium that's from the horse. If you're going to use a probiotic for a dog, it should be from the dog. If you're going to use a probiotic for the human, it should be a bacterium that was cultured from — originated from — a human. So that's what I mean by species specificity.


                    The reason for that is that, if you take a dog bacterium and give it to a horse, most of the probiotics that are of significance lived along the surface of the gastrointestinal tract. The organisms that digest feed live internally in the gastrointestinal tract. The probiotics live along the surface. So, if you're a dog bacterium, you're probably not going to attach to and live on the surface of the gastrointestinal tract — the surface cells of the gastrointestinal tract of the horse. So that's why species specificity is important.


                    Now, that's not always 100-percent true. There is some thought that some of the dog bacteria in the gastrointestinal tract are very similar to human bacteria and may live together very well. The reason is because the dog and the human have evolved together for so long. So, maybe that case is different, but there are probiotics on the market now that are cheese culture bacteria. Why are you giving bacteria that makes cheese to a horse? You need a bacterium from that individual, that's been cultured from that individual and, then, will have the ability to live on the surface and reproduce and grow on the surface of that species.


                    The other thing is that it's very important to give live bacteria. Dead bacteria will have only some benefit.


Nicole:         How can you tell if it's alive or dead?


William:         Well, it should have a guarantee, but oftentimes those guarantees aren't very accurate. But it should have a guarantee of live bacteria at time of use. Then, you want to look at the type of product packaging. If it's a container with a lid, you're very unlikely to have live bacteria. The reason for that is, as soon as you take that lid off, there is going to be exposure to moisture in the air, and bacteria there in probiotics are generally lyophilized or freeze-dried. Those freeze-dried bacteria, when exposed to moisture, will come to life. They're not dead because they've been freeze-dried, but they'll be able to start to reproduce. If they're not in an environment where they can live, they're going to die. They're not from a container. They can't live in the container unless they're lyophilized.


                    A product needs to be an individual dosage product, like a sachel or a packet, or it needs to be in something that is hydrophobic — something that doesn't like water, like an oil base or a paste that's oil-based — or potentially a tablet. Certainly, one of the worst things would be just a container you take a scoop out of. Those bacteria are unlikely to be alive. So, live bacteria are very important.


                    The other thing, besides species specificity and live bacteria, would be numbers. If you see it has a million bacteria per dose, that's not very good. We're probably needing billions of bacteria per dose. Now, if you're giving a sick animal —because probiotics can be very useful for a sick animal with gastrointestinal disease — there are two ways to think about giving probiotics. One is your sick patient, and that's where I got my interest in probiotics — my specialty is in internal medicine. I treat a lot of horses with gastrointestinal disease, enterocolitis — which is a fancy name for diarrhea — and probiotics, to me, are very helpful for treatment and recovery, probably more so for recovery of returning to a normal stool. The other way that probiotics are given is more as a daily.


                    So, you're giving a sick animal a probiotic — you want to give a horse 20 billion to 50 billion. If you're giving a daily, you can get a lower number, but it should still be in the billions, because the idea with a daily is to continually replenish that important bacteria.


Nicole:         If a horse owner is looking at getting into probiotics, can they just get it over-the-counter, or would you recommend them going to their vet?


William:         I think you can do either/or. Honestly, when I was in veterinary school, we learned a lot about bacteria, but we learned about bad bacteria. The good bacteria were those bacteria that were in cows and horses — or ruminant and non-ruminant herbivores — that digested the feed stuffs. We learned about those bacteria, and we learned about the bad bacteria: Salmonella, E. coli, Clostridium, et cetera. But we didn't spend a lot of time learning about the good bacteria and what they actually do and how they do it, which is fascinating, and it’s a more an evolving science.


                    So, as a veterinarian, I can say that a lot of veterinarians don't really have the knowledge about probiotics. Obviously, as a veterinarian, I'm not trying to be critical of veterinarians, but I didn't understand either until I looked into it.


                    I think you can do either/or. You can have conversations with your veterinarian or you can go to where you buy your supplements and ask, but look for things with live bacteria, large numbers and species specificity.


Nicole:         What made you look in this direction? Was it the veterinary feed directive coming into play?


William:         No, and that's a good question. I'll tell you: what got me interested in this was my patients. When I had an active veterinary practice, I worked in a hospital and I had sick horses. We would have our rounds in the morning, and students and interns and residents would ask me, "Well, why are we not using probiotics?" They were coming out of school with more knowledge about probiotics than I had, so they were asking me questions about not using a probiotic. What I'd learned with time is [to] never disagree — some students may know a lot more about some things than you do, so be careful — but I didn't really know until I looked into it. It's because we didn't have good bacteria. The bacteria were dead. At that time, there was a veterinarian in Canada at the University of Guelph who cultured ten of the probiotics that were available, and they all had dead bacteria. A lot of them had bacteria that were from other species or cheese cultures, etc.


                    So that's what started me into it. I was trying to help my patients because, to treat a horse with diarrhea, we were limited. Yes, we can use antibiotics, but we had to be careful because we may even be killing more gastrointestinal bacteria. We used bismuth subsalicylate, which is basically Pepto-Bismol. We used charcoal to try to bind toxins. There's a lot of things we have, but we didn't have something really good to replace the flora of the gastrointestinal tract.


Nicole:         What kind of changes in performance have you witnessed in preventive nutritional plans versus pharmacological treatment?


William:         That's a really good question, because I love that word, “preventative.” If you think about it, as veterinarians, what preventatives do we practice in our backyard horses, in our athletes, in our breeding horses? Vaccinations? That's a preventative. Deworming, treating parasites or preventing parasites — that's a preventative. We've been doing that for years. We haven't really addressed the gastrointestinal tract as far as the flora at all. I think it's potentially an inexpensive way, particularly in young animals or young horses you're raising.


                    There's been some work done in humans that has shown how important that certain bacteria are to the development of the immune system. One of the bacteria that I'm most interested is called Lactobacillus reuteri, and this bacterium is critical to the development of an infant's immune system — not only in the horse, dog or the cow, but to humans. If you think about it, what have we done in human medicine in raising a newborn that has changed their flora the most? Where does the infant get its flora?


Nicole:         Its mother.


William:         Its mother, correct. It gets it from passage through the birth canal and from feeding. So, what have we done? We feed a lot of milk replacer — or, as it’s called for humans, infant formula. We do a lot of cesarian sections in humans, so they don't get their flora. The flora is critical. There have been studies that have shown that adding Lactobacillus reuteri back to some of these infant formulas has produced a healthier child. Studies have been done in mice and other species with Lactobacillus reuteri to show how some of these effects occur and develop the immune system.


Nicole:         What would you say is the current owner or industry perception of probiotics, and how do you see it evolving?


William:         I think it's a matter of education. I really do. I think that we see a lot of human probiotics being advertised on television, so people have the knowledge of a probiotic, but I don't think they have the knowledge of the importance of species specificity, the importance of live bacteria, et cetera. I think those are the things that people don't understand — not that they should, because they just haven't been told. They're not exposed to that information. But I think the perception and use of probiotics is going to expand when we see what it can do.


Nicole:         Dr. William Bernard is an equestrian veterinarian in Lexington, Kentucky. Thank you so much.


William:         Thank you.



I want to learn more about improving horse health and performance!