Decomplexicating Equine Nutrition Part 04 of 12 – Gut Inflammation

~ (Above) The woods in winter (above) are seen along the road in Washington. The branches remind me of the convoluted and expansive brush-like gut lining ~

Quick review:

Part 1 – Grazers versus browsers – Discussed the difference between glucose, starch, cellulose and lignin. These are all made of the atoms Carbon, Hydrogen and Oxygen but put together is different ways to form these molecules. Glucose is the main molecule and a chain of glucose molecules joined in a specific way is called starch. Both glucose and starch are directly digested by all animals including the horse. When the chain of glucose is joined in a different way it is called cellulose and cannot be digested by animals but it is digested into short-chained fats by the bacteria in the gut. Horses with their very large colons are designed to consume large amounts of fat-producing cellulose and NOT sugar-producing starches.

Part 2 – The Basics of Sugar, Fat and Proteins – Discussed how not only sugar but fats and proteins are also made of Carbon, Hydrogen and Oxygen but put together in different ways. Proteins add a Nitrogen atom which can be removed so that a protein can become a sugar. Grass provides for the horse both starch (which becomes sugar) and cellulose (which becomes fat). Both sugar and fat are fuels used by cells to make energy. In nature there are seasons when starch (sugar) is abundant to add body fat for winter and then during seasons when starch is not available (winter), the cellulose consumed and the stored body fat provide the fuel for energy. It becomes a natural ebb and flow of fat gain and fat loss caused by the varying forms of seasonal fuel. However, the continuous availability of starch (grains) prevents this and causes diseases in the horse (and in humans).

Part 3 – Gut Microbes  – There are 8 times more bacteria in the gut, the skin and in the air around animals than there are cells in the body. The horse is really feeding the bacteria and in turn, they feed the horse. When the bacteria are fed correctly then they provide the horse with all they need to thrive. When they are fed incorrectly then the bacteria die and are replaced with bacteria that live on the bad food. While surviving, this results in materials that can damage the gut lining and create inflammation. This is today’s blog discussion.

When the Gut Wall Becomes Damaged and Leaks

Think of an un-frosted doughnut. Do you see that the skin of the doughnut is the same on the outside of it as well as on the inside of the hole?  The hole is a continuation of the skin on the outside. The digestive system is like a long doughnut hole or tunnel (see my blog “Doughnut Hole”). It starts at the mouth and goes through the horse to the anus. Another way to look at this is to visualize a car tunnel under water or a subway under a city. It is free of the water or dirt that is on the other side of the tunnel and is filled with air from the outside from the holes at each end. In other words, in the digestive tract of your horse, what is inside the stomach and intestines is OUTSIDE of the body.

If you need proof of this just ask anyone who has torn a hole in their guts and let the gut material go into the space where the liver, kidneys or lungs live. But you can’t ask them because they are all dead! What is inside the gut must stay inside the tunnel. But how then does the food the horse eats fuel them to live? We need to start with the lining of the gut wall.

The lining of the gut wall is basically the continuation of the skin with the following similarities and one major difference. Both keep the bad things out and the good things in. Both have a way to heal when damaged. Both regenerate their layers. Both are covered with bacteria in identifiable groups. But with the exception of very few things (for example DMSO on the skin) the skin cannot let in specific molecules. The lining of the gut is modified however to allow in specific molecules while keeping out other molecules and invading bacteria such as e.coli. This selective absorption of certain molecules is really a remarkable feature.

The lining of the gut is expansive if stretched out and smoothed. Because of the velvet-like undulations of the lining, this huge surface area is condensed to fit inside the horse. Of great importance is the fact that the lining of this tube has only one cell layer that is active with many layers of immature cells underneath ready to replace this delicate membrane as it ages and is sloughed. Between each gut cell is something called a tight junction which is impervious to everything – until it is damaged and then it leaks.

Damage to these tight junctions is caused by several things. The first is inappropriate acid production that can burn and ulcerate the membrane (the cells and the tight junctions) just like a sunburn ulcerates our skin. This acid can come from the overproduction of hydrochloric acid (HCl) in an empty stomach exposing the non-glandular portion and causing a gastric ulcer. It can also be caused by the overgrowth of bad bacteria from chronic sugar intake (grain) in the colon creating colonic ulcers (ulcers of the colon).

As the bad bacteria take over, most of the good bacteria die and break apart into little pieces called lipopolysaccharides (LPSs) and these attach to inflammatory fats (such as vegetable oils) and are transported across the gut membrane through the tight junctions into the body. These become inflammatory materials that the horse reacts to resulting in a general feeling of unease to overt unwanted behavior (bucking, kicking).

Another cause of damage to tight junctions is by plant proteins that are foreign to the horse. These are called lectins and they physically break down the tight junction and enter the body where they cause inflammation and overtax the immune system, disrupt hormone communication through mimicry and deplete the energy from cells either through exhausting the mitochondria or by starving the cells (more about this in another future blog).

Gluten is a well-known lectin that most people know about. Some people sensitive to gluten have severe health issues related to its ingestion. But gluten from wheat is only one of the thousands of lectins we know about in human medicine. Most of these damaging plant proteins are found in the skin and seeds of plants and are found in the skins of ALL grains (wheat, rice, corn, barley and others) causing gut inflammation in most horses and humans. Nightshades (tomatoes, cucumbers, eggplant, squash, peppers, and more) also have severe inflammatory lectins but these are usually not fed to horses.

Foods that horses have eaten over their 55 million years of existence have adapted to the horse and the horse has adapted to them. Because of this, horses are OK with the many plants they graze on. Occasionally a horse will find something he is not used to throughout most of the year but in the short time it is available (apples in the fall), they eat without much problem. This is because ripe fruit removes its lectins from the skin. As you know, eating unripe fruit is not only distasteful but it can make you very sick (green apples).

A Dr. Seuss-like apple tree in the Washington winter morning. While this fruit is available, it is out of season and therefore would have lectins in the skin.

The foods introduced to the horse’s diet have not adapted to become the cause of many dysfunctions and diseases. Adaptation to new foods takes tens of thousands of years and certainly a lot more than the 4000 years we have domesticated them. In the 45 years, I have been with horses and when talking with other horse owners who have been with them even longer, horses were rarely fed grain on a regular basis. In the past 30 or so years, the marketing of grains to horse owners has now made the caregivers feel less than worthy if they are not feeding grains year-round to their horses. I often hear people respond to my no-grain challenge with this question, “But how will he get his nutrients?”

They have lived 54,999,950 years without grain. Going for 2 weeks without grain will not kill them and will perhaps help you see the positive changes in your horses when fed the way they were made – with food adapted to their good bacteria.

But there is more. It’s not just the whole grains causing the gut damage. Grain byproducts are what is left over when the offending lectin-laden skin is removed (wheat germ, wheat middlings, rice bran, oat hulls, sugar beet pulp). Rather than discard this, grain manufacturers have found a new home for them as fillers in horse feed. And of course, there is more.

The storage of grain is not usually in climate-controlled and dry areas. Because of this, most corn in the United States (and coffee beans for that matter) have mold growing on it. These molds of course are on the outer layers and that is exactly what we are getting when grain byproducts are put into animal feed. The same holds true for whole grains. Mold-damaged grains are less expensive and because of this are used in many animal feeds where human consumption of the animal does not occur (the best grains are fed to animals before slaughter). I have yet to see a bag of horse feed that says “Our grains are tested and are mold-free.” Forgive me if there is one but it is not a mainstream feed.

The continuous feeding of sugars from the starch of grain, the lectins of grains and the molds of grains all contribute to the gut wall being damaged which then leaks inflammatory materials into the body. This leads to the disruption of the power plants of the cells (the mitochondria – in another future blog) which leads to dysfunction of many body systems which leads to most if not all of the diseases we see in horses today.

The problem is that all of this information is between 2 and 10 years old and is mostly found in human studies. It is only starting to get into equine nutrition. But step into my time machine for a moment and let’s go back 45 years. Did you know suspensory injuries are now at epidemic levels but in 1973 were very rare? The dropped hind limb fetlocks that devastate horses and cause their fetlocks to drop to the ground were not even in the textbooks when I went to Cornell’s vet school in the early 1980s. Developmental orthopedic disease in foals (OCD, epiphysitis, contracted tendons) became common in the 1990s and was only found on farms where grain was fed. Pituitary dysfunction (PPID) occurred but not to the extent it does now. In humans, dopamine resistance is related to sugar consumption. Pergolide, the drug used in treating PPID or Cushing’s disease, is a dopamine replacement. Hmmm… is there a connection here?

Finally, the real problem needs to be addressed. There is no money for research to assess the health benefits of not feeding grain. Grain is a multi-trillion dollar business and it does not want to hear that grain may be causing disease in horses. Most people new to horses (30 years or less) only know how to feed horses using grain, grain byproducts, vegetable oils, sugar cubes, carrots and apples and trust the dealer to do no harm to their horse. Ask yourself, “Is what you are feeding your horse working?” Is he fit like an athlete or does he have Cushing’s, metabolic syndrome, laminitis, colic, suspensory injuries, cracked or malformed hooves, poor top line, skin conditions, anhydrosis (non-sweating), bad behavior (girthy, bucks, can’t clip, can’t load on a trailer), diarrhea or squirts, insulin resistance or any other issue you can’t seem to resolve?

All of these can be related to gut inflammation and the breakdown of the gut wall and leakage of contents into the horse’s body.

Next up is a discussion of what mitochondria are and how they work. This will be followed by a discussion of carbohydrate dependency because all horses need sugar, just not all the time. These will be fascinating for those of you following these blogs and wanting to learn exactly how their horse works.


The foods eaten by horses for millions of years do not cause gut inflammation.

New foods introduced in the past few decades cause gut inflammation from the lectins, molds and starch (sugar).

Gut inflammation is very likely to be the root cause of most problems and diseases of horses seen today.

Removing the inflammatory foods is easier and a more holistic approach to solving problems in horses than adding any supplement, medicine or treatment. However, before you remove any of these, you MUST consult your veterinarian and discuss your individual horse and act accordingly with an agreed plan.

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  1. I have had my horses on the no grain diet for 2 months. They are so much easier to work with. The 17 year old had chronic shoe boils on his elbows. They are completely gone now! I would like to know what joint supplement you would recommend for him. The ones I was using have a lot of sugar in them. I have also started them back on Biovigor. What do you think of that supplement?

    1. All joint supplements (glucosamine) are oligosaccharides (a sugar) which binds to the lectins of grains to prevent these joint inflammation makers from entering the body. In other words the “joint supplement” never enters the body but works within the gut. However if there are no inflammatory ingredients (grains and grain byproducts) then there is no need for joint supplements. Just send me the money you spent on them….

      I do not know Biovigor and no longer look up every supplement people ask me about because the answer is always the same. If the gut microbes are normal and the gut inflammation is gone then the horse doesn’t need any supplements. The gut bacteria make all the vitamins and the minerals come from the water and mined salt. Healthy horses need no supplements.

    1. PPID is Pars Pituitary Intermedia Dysfunction. This is part of Cushing’s Disease where the hypothalamus sends a signal to the pituitary to send another signal (ACTH) to the adrenals to produce cortisol. The problem is that the signal from the hypothalamus to the pituitary is never received. A dopamine like drug is administered (pergolide) to stop the pituitary from producing ACTH which in turn decreases cortisol production from the adrenals.

      It is my hypothesis that this is part of the protein deficiency and this deficiency stems from either an inadequate consumption of all the essential amino acids from a good quality protein or the decreased absorption from gut inflammation caused from grain, grain supplements, treats and even many medications.

      With your horses never being fed grain you can rule out grain induced gut inflammation. This leaves inadequate broad spectrum amino acid availability in the diet which is common in poor pastures or pastures and hay of only one type of grass. Many horses have reported their ability to remove their horses from cushing’s medication after removing causes of gut inflammation and the addition of a good quality protein source such as soybean meal.

  2. I stopped feeding grain to my two horses (ages 20 & 17) within a week of your first article. My quarter horse was always ‘girthy’ and the Tennessee Walker has shown signs of a weakening immune system for 3 years (coughs). I offered more hay this winter, added some soaked beet pulp (no sugars) and they are doing great – very little coughing and I’m pretty sure the flattening of the ears when saddling up is more a habit/bluff than hurting. No loss of top line or muscle overall. I had forgotten about the pure salt block and will get one this week. Thank you for the clear explanations.

  3. A very interesting and enlightening article. What types of food would you suggest horses be fed? Thanks, Janine

    1. Pasture and hay, water, pure salt. If they show signs of protein deficiency (poor top line, loss of masseter muscle, poor hoof condition, lameness and connective tissue breakdowns, others) then after the gut is calm and healed (2 to 6 weeks) add a variety of protein.

      It is that simple. Please read the articles on chronic protein deficiency to learn more and stay tuned because there will be more about this.

  4. I really enjoy all of your blogs and articles; thank you for making this available. What are your thoughts on the low starch/low sugar high fat (typically oil) diet for EPSM /PSSM horses? It seems to make a dramatic difference for many horses that DNA test positive for PSSM1, and the diet aligns with much of your philosophy right up to the oil, but this high fat component is a crucial piece. Do you suggest another way to achieve the fat ratio for these horses, or do you have other thoughts on dietary management for documented PSSM1 horses, or are they an example of “the exception that proves the rule”?

    Thanks again.

    1. Polysaccharide storage myopathy or “tying up” has been found to be a DNA break where excess saccharides (sugars) will cause muscle cramping. The time tested low sugar / high fat diet works well on these horses.

      What is now known is that certain oils are inflammatory to the gut and may cause gut leakage. While no one has done the study on this in horses, it is known that all vegetable oils in humans may be inflammatory. The idea behind feeding fats is discussed in the next blog where the 2 fuels (glucose and ketones) used in energy production are discussed. The goal in these horses is to reduce the glucose and increase the ketones.

      The primary source of ketones is the breakdown of cellulose by the gut microbes into short chain fatty acids. The more cellulose fed, the more ketones produced. Unfortunately all pasture and hay have starch (glucose) which is not tolerated by horses with PSSM. Adding oil will increase the ketone production and will “cover up” the starch intake to a point. In humans, the 3 oils that seem to be noninflammatory are unspoiled olive oil, macadamia nut oil and avocado oil. Coconut oil is also very effective in providing ketones without inflammation but it has 6 fractions and 2 of them are inflammatory, 3 are not but need to be converted to ketones, and 1 is actually pure ketones. This said, I recommend coconut oil or even coconut meal for a fat source for horses as most do really well on it.

      The bottom line is avoid globbing on cheap vegetable or corn oil especially if your horse shows signs of gut inflammation including developing fat pads. Consider olive oil or coconut oil instead.

  5. Thank you so much for the good information. It really helps me understand how , all the companies are getting rich off us horse people. I am working toward being grain free. I have a 31 year old horse, will she do ok on soaked hay cubes?

    1. She will do better without the grain but she may need more. I have more blogs coming but unfortunately, I want to go step by step teaching the why so changing will become easier for horse owners. How to do it will be coming.

    2. Hi Marianne, I have a 32 yr. old who’s teeth were over filed and can not chew hay. I’ve been feeding him alfafa hay cubes which I know are bad for horses but you can’t get straight timothy cubes as far as I can see. I also give him senior feed via auto feeder every two hours because they are a grazing animals but I’ll need to switch him off of that slowly but the forage/grass pellets only come as alf/tim and are very hard. I hope Doc T touches on this also. I love reading his articles. Good luck with your older horse 🙂

      1. I feel the opposite about alfalfa. In most horses alfalfa is a very good food but some do have a reaction to it (diarrhea, anxious), but most do well on it. At 32 years, if your horse likes alfalfa then keep feeding it.

        All grains, on the other hand, will cause inflammation. But an important point needs to be made here. If an older horse is “doing well” on a senior feed and some hay cubes, then be careful changing anything especially in the winter. The first thing they do is lose body fat and the loss of muscle in the top line becomes very evident. This freaks out owners.

        Auto feeding a starch source keeps the mitochondria working around the clock adding to their exhaustion. In humans, intermittent fasting really helps the mitochondria rest. This entails not eating for 16 to 18 hours and placing all food intake within a 6 to 8 hour window. In horses who are truly continuous eaters (no gall bladder, hypsodont teeth) I agree that they should have access to cellulose (pasture or hay) all the time. Pasture will have a limited amount of starch in the winter and hay will have a variable amount depending on the batch. But having access to a concentrated starch source loaded with lictin filled grain byproducts will just inflame the gut, promote leaky gut and disrupt the insulin system while exhausting the mitochondria.

        This said, as I said in another reply, at 32 years, if he is doing OK with your system, be careful rocking the boat. Changing things now at his age may not give the desired results. Better to wait for pasture to appear and wean him off of grain then.

        1. Thank you for the reply. My other horse (mare) who has chronic lyme disease and chronic founder was raised as a filly on alfafa and oats (straight) ..she has been a mess most of her life. I blamed the alfafa as I read from some experts “it’s not horse hay” Maybe it was the oats, who knows. She had only a seven year break with no issues and I was feeding organic oats and barley in very small quantities, grass hay and pasture. Maybe it the chemical that is sprayed on the grains before processing too. This lyme disease is horrible to connective tissue, she is almost 22 now and I want to get her feeling better. I appreciate you very much and I wish you lived close by. I would hire you! Have a great day 🙂

          1. Thanks! By the way, in 1932 researchers studied children who were having excessive cavities in their teeth. They determined that it was their daily morning oatmeal causing it (lectins?). When this was removed and Vitamin D was added, their cavities either stopped developing or, in some, actually repaired. While whole oats have been fed to horses for years, the oats of today are probably not the oats of yesteryear due to GMO and farming yield practices.

  6. Geoff: the best of the series so far. You have a truly remarkable way of explaining the complex in ways an ordinary mortal can comprehend: “Decomplexicating”. No doubt, every feed company and many pharmaceutical companies are grinding their teeth right now, but this should be posted in every horse barn in the world!!

    1. So grateful for your comment here.

      John is a friend of mine and is the owner of Freedom Health LLC which is the maker of SUCCEED© ( ). Every year I vow to put him out of business, but as long as people insist on feeding grain, John will continue making his amazing product for helping horses with colonic ulcers.

      As I say in this blog, it is better to remove the cause than treat it. For those who disagree with this, get SUCCEED© today.