Symbiosis And The Horse’s Gut

I am trying to make sense of things but I keep coming up short when determining why grain causes so many issues in horses. My search has led me to an idea that is based on research in human nutrition.  In this and blogs I am writing over the next several weeks I will introduce you to these concepts to help you and more importantly your horse.  They may take several reads to understand but I will make this promise.  If you read and re-read this and every article to the end your horses will live a more healthy and vibrant life.  It may take some mental effort on your part now but the rewards you will have with your horses later more than make up for this.  (Go here to understand the benefits of removing grain from your horse’s diet.)

Of course horses are not humans especially when it comes to the system that digests the eaten food.  For a moment though, let’s look at the similarities. Horses and humans both consume the same 7 things: air, water, electrolytes, minerals, sugar, fat and protein. Also in common is that whatever we bring into our bodies by swallowing is NOT inside of us. This is where it gets interesting. Nothing we eat is allowed into our bodies unless it is first broken down into molecules. These are very small and invisible to us but they do exist. Incredibly what makes these molecules that become absorbed into us and our horse are the gut microbes. We are actually feeding them and in turn, they feed us. This is a symbiotic relationship where two different organisms live closely together in a beneficial way.

A Perfect World

In a perfect world, we eat perfect food that was digested by groups of perfect bacteria spread throughout our GIT (gastrointestinal tract). These bacteria convert the food we feed them (the food they want and need to thrive) into the food we need to thrive. Included in this conversion is the bacteria’s ability to convert complex sugar (fiber) into fat which we absorbed for energy. That’s right! The green leafy vegetables of our salad is the complex sugar that our bacteria want. They in turn convert it into fat molecules our bodies absorb to thrive on. As such the salad can be considered a high fat diet. Just look at the example of the strength of our horses eating only pasture grasses.

The cells that make up humans and horses get energy from only 2 fuels: glucose (a sugar molecule) and ketones (a fat molecule). Either can fuel the furnace in the cell (the mitochondria) by supplying the energy needed to create the power to keep things alive. Think of the mitochondria as a generator that produces electricity when turned by a fuel such as wind (wind turbine), water (hydroelectric) or gas engine. Glucose or ketones are the fuel driving the generator within the mitochondria (the Krebs cycle) in every cell in the body.

But this isn’t a perfect world especially in the past 50 years. Our diets and that of the horse have dramatically changed and along with that the GIT bacteria have changed. Imagine a small town clean and vibrant with affluence filled with friendly families. The sun shines, flowers grow, children are safe on the streets, no crime – you get the idea. One day something changes and gangs are formed, crime erupts, pollution and sewage fill the streets and buildings decay. The town still exists and can be found on the map but it is no longer a healthy place to live.

What changed?

The “something” that changed this town, known as the GIT in humans and horses, is the food we started to feed the gut bacteria inhabiting the town. This altered food source has done two very bad things. First it caused the death of many of the normal or “good” bacteria and replaced them with opportunistic “bad” bacteria that do not supply the body with the nutrients we require to thrive. In addition both the new “bad” bacteria and the dead “good” bacteria break up into little pieces of cell debris called LPS (lipopolysaccharides) which are toxic to the gut wall causing inflammation and a leaking intestinal wall.

If that isn’t enough, some of these new foods were never eaten by us or the horse in the past and therefore they are foreign to our immune system. Like a splinter under the skin, a small infection starts at the gut wall caused by these foreign foods. But it gets worse. These foreign plants and seeds are pissed off. They too want to survive and don’t want to be eaten and die. In order to survive, these plants develop proteins that weaken and even kill animals that eat them.

There is more to discuss in future articles but I’m ending this here to give you a chance to become comfortable with the basic premise that we are feeding the bacterial microbes in our digestive tracts and they in turn are feeding us. Horses and humans have been around for several hundred times longer than the few thousand years grains (corn, wheat, oats and others) have existed as a common food source. I believe this is the reason why so many horses that have had grain removed from their diets have had success in resolving behavior and medical issues. It is the battle of survival of 1) the plant proteins (called lectins) and 2) the disruption of the normal “good” gut bacteria wrecking havoc on the peaceful village within the GIT.

Coming up:

What exactly are lectins? What is a leaking gut wall? How is insulin resistance related to this? How is a poor top line related to this? and more…


    1. Rebecca – Would you p[lease double check the link as this one goes nowhere.

      I am noticing that EVERYONE is now using terms like microbiome. It is suspicious. And I am suspicious of ANY company doing a project. Last December I sat through 2 presentations given by Purina and Nutrena. The vets had their hands scribbling notes between the free food being eaten at these 6:30 am sessions. I sat listening and was aghast at the blatant marketing, misinformation and purposeful absence of material. I wrote a blog about it here.

      I apologize in advance for being cynical. Research must be done by unbiased people. Thanks for asking my opinion and feel free to repost the correct link and I’ll look at it.

        1. Ah – that’s better. what they are trying to do is create a roster of the microbe content in the feces of horses. They have done this in humans and I believe in Wales they have done this in horses as well.

          This past January I submitted my sample to see what was in my gut. But what to do with this after sampling is the question. I received many suggestions and now they want me to resubmit after I have made the diet changes they recommended.

          In sampling the horses it would be interesting if they also compared what they find with what they were fed. I’m not sure if sampling the feces is as effective as sampling several spots throughout the gut but to do this would require major surgery or sampling very soon after death. For me, the coupling of the data with the history of diet and age / breed / gender and of other environmental factors (mono feed pasture versus a broad variety of plants) would be revealing. But in the meantime I think everyone should submit a sample.

          The company in Great Britain (I think Wales) also sells a probiotic which they suggest the owner purchase to complement the sample results. Platinum Performance will also try to monetize the results. Let’s watch and see what comes of this and thanks for bringing this to our attention.

  1. […] there to feed the bacteria living in your Gastro-Intestinal Tract (GIT) and in turn, they feed us (Symbiosis). When something new is introduced to our GIT such as a foreign protein of a new food (a lectin), […]

  2. I was fortunate enough to have started my horse experience with a group that looking back was ahead of its time in horse management. In those days it even landed the owner of the herd in a battle with the Humane Society for not feeding grain and allowing the horses to roam freely to drink from streams and forage for grass. Gasp! No stalls! It all comes down to putting animals in environments where they were never intended to be. The lush pastures and yes the grain mentality still continues. I have to admit I still struggle when I look out to see my drafts and mini donkeys on a dry lot with plenty of grass hay but regulated pasture access. It’s clear to me that the gut biome is so much more complicated and implicit in our animals health than we can imagine. Thanks for shedding light on a discussion that unfortunately not enough vets are willing to have with their clients. I continue to be disappointed in the industry that chooses to ignore the data. I suspect it has resulted in many turning to extreme fringe practices in the name of natural and horses suffering.

  3. I put my 17 y/o QH on your no grain challenge in an attempt to help his anhidrosis. I wrote to you about him on the No Sweat post. Buddy started sweating on day 3 and has continued to sweat ever since. In fact, this morning I did a 2 hour trail ride and Buddy was slick wet over his entire body. He was also forward and raring to go for the entire ride. He is obviously feeling really good.

    Interestingly, Buddy had also suffered from chronic diarrhea since last October. Gut improvement was slower to come, but he has had slow, steady improvement in his diarrhea since the change in diet. At this point his manure is totally normal and he has had no diarrhea in the last month or more. Even after a fast and long trail ride and a trailer ride home the manure in the trailer was picture perfect today.

    I look forward to your future articles on diet. You have certainly made a believer out of me. I am forever grateful to you – you have given me back my horse. In live in hot and humid S. Carolina and I was literally only able to ride Buddy during the few cool months of the year. Thank you, thank you, thank you.

  4. I too compare human and horse health sometimes. What I haven’t been able to get my head around is whether or not horses’ natural diets in the wild provided them with good bacteria as a human diet used to when we ate a lot of fermented food. Humans seem to get healthier when we actively consume good bacteria (probiotics). Eating prebiotics (food for the good bacteria) helps keep us healthy but on its own, without actually consuming probiotics too, doesn’t seem to be enough. I guess I’m saying that humans need to continue to replenish their good bacteria and not just feed them, especially after we’ve been on antibiotics. So I suspect that horses, especially if they’ve been given antibiotics, need to replenish their good bacteria too. I stopped feeding grain to my horse years ago but I continued to feed probiotics and I could tell the difference in his health. I suspect, their diets, in the wild, also provided good bacteria but how? Does good bacteria exist out there in the wild for the horses to find? If it does, then wouldn’t we need to provide it to them when they’re domesticated?

    1. I don’t have all the answers on this because little research has been done on the horse’s holobiome / microbiome. In humans infants pick up most of their gut bacteria from the birth canal during natural delivery. Many look at coprophagy (eating manure) by foals as a way they seed their gut. There is evidence that the good bacteria still exist in the gut but are suppressed by the overwhelm of the bad bacteria, but most of the good bacteria are starved by improper food or killed by antibiotics.

      If I were to guess, I would consider dosing the horse with good bacteria when given broad spectrum antibiotics. Otherwise I would rely on the natural reestablishment of gut microbes after removal of all inflammatory agents and allowing time for the gut to heal (6 weeks) plus another 4 to 8 weeks.

      More is needed on this but I am convinced by my observations that decreasing inflammation is step one. Easier said than done, I know.

  5. Under the what changed section.. We started spraying the grains with Glyphosate and a lot of it. It’s shown to kill and cause the gut microbial to change and go bad. It can cause a potential cascade of ill health to death in humans, fish and chickens..starting in the gut.. It seems under studied in horses. But a rash of health issues have shown up since we started that and adding a lot of other things to our and the rest of the animal’s diets. It’s hard to totally agree with the sentence that foreign plants and seeds are getting pissed off when some of what we are now feeding is not food or a living thing at all…is things like cotton seed hulls, Ag/food industry trash, cardboard & such…anything cheaper than real, whole food. Was amazed at feed trials at Clemson..what we were trying to make into “food”. Cardboard was a common base. Real feed costs money. Organic Horse Feed is $34.50 for 50# in East Central Florida but can be worth it if grain is a must. None of this changes some bad aspects of feeding grain like it heating up an already hot horse or providing too much protein and energy to some confined horses making them have a hot attitude and such.

    1. Hi Holly – This subject is something I was struggling with one question – where do I start? So I decided to jump in here to start the discussion of why we are developing a leaking gut from inflammation. It really is the root of most of the problems seen in horses and humans. Magnifying this is glyphosate (Round Up) as well as genetic modification (adding foreign lectins to plants), antibiotics, non-steroidal anti-inflammatories and feeding sugar (grains) when not in season and added blue florescent light (altered circadian rhythm). All add to the problem of lectin damage to the gut wall which confuses the immune system and mimics insulin.

      So you see this is a huge subject of which glyphosates is a part of. I also understand that some companies add non-food ingredients to animal feed. I see this every time I’m asked to read a feed label. But beware of organic feed because the lectins are still there and that’s what is starting the problem. Horses don’t need grain whether it is organic or not. If grains were a normal feed for horses (or humans) there would be a place somewhere on this Earth where it was available to the horse every day.

      In the past decade researchers have discovered wheat germ agglutinin (WGA) in wheat bran that once in humans mimics insulin preventing it from doing its job. It may be why insulin resistance has increased at an alarming rate in humans and horses.

      But I’m getting ahead of myself. Stay tuned…. and thanks for your input 🙂

  6. What can be done to improve a horses good bacteria once we eliminate all grain?

    1. The good bacteria are still there but suppressed or overwhelmed. The gut should repopulate once the leaking gut fully heals in about 6 weeks. The good news is that you will see a difference in your horses in as little as 10 days.

      Be sure to hunt out the hidden grains and lectins in other things such as carrots, red salt mineral licks and horse cookies.

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