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The Gut System

- the Mother of all the Systems

Ulcers, Leaky Gut or a damaged Microbiome? Either way, they're all connected.

Principal Body System: Digestive

Definition: A long tube called the gastrointestinal (GI) tract and associated organs, i.e. salivary glands, liver and pancreas.

Function: Performs the physical and chemical breakdown and absorption of food for use by cells, and eliminates solid and other waste.

All dis-ease begins with the gut. So said Hippocrates, who was way ahead of his time, as all these centuries later, there's no doubt about it. The digestive system is the Mother of all the Systems, and the large intestine the Mother of all Organs - everything starts with the gut.

A healthy gut is the ultimate gatekeeper of good health, and a healthy microbiome the game-changer - this may be the decade, or even the century, of the microbiome. The gut microbiome is probably the most important regulator of health. There are 100-trillion microbes sending messages throughout the body - interacting with hormones, immune system, brain chemistry, and every other system in the body. When the microbiome's microbes are are out of balance, a seriously malfunctioning body is the result, simple as that.

The gut system isn't just a tube where we shovel food in one end and wait for it to come out the other end - the whole gut system, from one end to the other, has a massive job to do inbetween, from initially breaking down the food (the foregut), separating out the essential nutrients (the microbiome), and getting them absorbed into the body to fuel it (the small intestine), while shuttling off the remaining waste to the main elimination exit point (the colon, aka large intestine, aka hindgut).

And it doesn't do all this by itself - the very function of the gut system relies entirely upon it's own army of elements; hydrochloric-acid to kickstart the foregut into action and kill off any nasties (it's how dogs survive eating other dogs' poop!); digestive enzymes to break down the protein, carbs and fats; microbes to assimilate the nutrients and break down the fibre, and fluids to lubricate and keep everything moving.

Without these essential elements, the gut system won't be able to do the very job it's meant to do, which is to keep the body alive. Without its own army it's no longer able to digest those essential nutrients we pay good money to feed to our horses to keep them healthy. Without them, so will begin a cascade of seriously chronic dis-ease. It really is as simple as this.

This life-dependent function relies entirely on maintaining a healthy inner gut environment, and the only way to do this is by feeding foods that boost the good bugs and weed out the bad bugs - this is critical for maintaining a healthy inner environment and preventing leaky gut syndrome, which these days is now rampant.

So, if you're looking to clear up the chronic symptoms that are chipping away at your horse's quality of life, there's only way to do it - clean up the gut system. We need to look after our horse's gut health first and foremost, as the top priority. And ... this applies as much to humans as horses too.

Digestion - it's not just about what we feed, it's about how it's digested

The horse's digestion operates via enzymatic digestion in the stomach, aka ‘foregut’, ahead of the large intestine, or ‘hindgut’, which is where we'll find the cecum and two colons, and this is where it's all about bacterial, aka microbial fermentation, of fibre.

This dual system works by the foregut dealing with most (over 50%) of the protein digestion and most soluble carbohydrate digestion. Fibrous sources such as grass and hay are digested microbially in the hindgut. And because our horses are meant to eat fibre, keeping the microbiome, aka friendly bacteria/flora/biota well-populated in the hindgut is right up there at the top of the list of priorities.

Horses normally consume 2-2.5% of their body weight in dry matter each day, although if they’re on pasture 24/7 this can go up to over 3%. By adding a feedbowl of processed feeds, the nutrient proportion from this will increase, so horses should reduce their total dry matter intake.

For enzymatic and microbial action to digest feed efficiently, the horse also needs healthy teeth to grind their feed to allow the enzymes and bacteria to attack the plant cell walls of what they're eating. Thus, it goes without saying that horses' teeth should be checked every year to ensure that they're wearing normally and are effectively grinding the feed.

Remarkably, the capacity of the stomach of the horse is small, about the size of a rugby ball and coming in at just 8 to 15-litres depending on horse-size. So it begs the question as to how a horse can consume such large amounts of food/water when constantly grazing. Easy - the emptying time of the stomach after filling is around 12-minutes, and the rate of passage down through the small intestine is about 1ft/minute - this means that food can go from the mouth to the cecum in about 1½ hours.

The small volume of the stomach and rapid passage of food from the stomach is the reason horses eat almost continuously, thus the term ‘trickle feeders’. Total passage time is 2-3 days from when food is ingested until it is passed out the other end.

NB. The foal and growing horse have undeveloped cecal and colonic digestion compared to the adult horse. There is very little microbial digestion before 3 months of age, so the foal requires a diet low in fibre and one that is easily digested in the foregut. Foals who are seen eating their mothers' droppings are thought to be obtaining a bacterial culture necessary for future microbial digestion.

Feed the Flora!

Collectively the beneficial and pathogenic microbes outnumber the regular cells in the whole, entire body, by an astonishing 10-1 - at least (!). Think about that for a second - there are a whopping 10-times more bugs in the gut system, that long tube from mouth to you-know-where, that in the entire rest of the physical body. Which means looking after our horse's gut microbiome is crucial, as amongst it's many vital roles, it's also the first line of defence against many serious diseases.

For starters, without a healthy microbiome, there's no nutrient absorption, which as we know is crucial to fuel a healthy body. But it's so much bigger than this - the microbiome literally runs the show. Around 80% of our horse's immunity is created by the gut microbes in the intestinal tract and this microbiota is also the major regulator of the immune system - the difference between healthy and unhealthy relies entirely upon the gut microbiome's performance.

Our part in nurturing a healthy microbiome is the first line of defence against many health issues. Our horses don't make their own gut microbes, so incorporating a probiotic into your horse's daily feed will help establish the colonisation of the beneficial microbes, enhancing your horse's ability to digest and utilise the full benefits of the nutrients you're feeding.

Unfortunately, there are also certain medical treatments which can really mess with the gut ecology, such as antibiotics, bute and chemical wormers, which disrupt the relationship in a similar way that chemotherapy affects the human body. Chemotherapy wipes out perfectly healthy non-cancerous cells inside the human body along with the cancerous cells, annihilating the immune system. Similarly, antibiotics wipe out the gut bacteria, the bad bugs as well as the good bugs the body can’t live without.

A healthy gut system is absolutely essential for overall health and vitality - sounds obvious I know but an effective digestive process means your horse will absorb the nutrients you spend a fortunte on trying to get into them. Again, it's a much bigger picture though; a healthy gut will also significantly minimise the laminitis/colic risk, and protect the horse against infections such as diarrhea-causing organisms like salmonella or clostridium.

The good news is that a healthy, functioning digestive system is really straightforward to manage - it really is, provided we feed them the right stuff, as in the food that their gut is meant to eat. Because ... the equine digestive system is also extremely sensitive, and it doesn't take much to upset the delicate gut environment; poor diet/dietary management, obviously, but chronic stress can equally play an enormous part in affecting gut health. Poor gut health can manifest itself in so many ways, from the obvious signs of loose droppings, lack of overall vitality, allergies or pain.

For the full story on how critical a part the microbiome plays in overall health, see our separate chapter below, The Microbiome - the Missing Organ? I promise you it's an eye-opening read ...

Leaky gut syndrome - introducing 'dysbiosis'

The lining of the gut is supposed to be strong and tight, keeping food, microbes and waste safely inside the digestive tract. So why is 'leaky gut syndrome' now becoming a new epidemic?

As above, I can't stress enough how important it is to centre our attention on the microbiome, and specifically those beneficial gut microbes, to avoid dysbiosis. To quote from Wiki, “Dysbiosis (also called dysbacteriosis) is a term for a microbial imbalance or maladaptation on or inside the body, such as an impaired microbiota.”

So here's another fact - it's the microbiome, as in a healthy one, filled with lots of happy, beneficial microbes busying away down there sorting out our nutrients, that regulates the permeability, aka leakiness, of the gut lining - this is the connecting factor.

When the gut bacteria balance is disrupted, whether from poor quality food, stressors or environmental toxins, and the balance between the friendly microbes and pathogenic bad-guy microbes reverses, those bad microbes set up camp and literally munch their way through the gut wall and split it open, which makes it permeable, and allows the undigested, seriously toxic matter in the small intestine to leak through the gut membrane and into the bloodstream. This triggers an almighty inflammatory autoimmune cascade as the immune system goes into hyper-overdrive, trying to fight those leaked toxins.

Cue the battlefield. Special immunoglobulins, also known as antibodies, live in the horse's gut to protect the body. The immunoglobulins IgA and IgM help identify the toxins, and begin the attack by calling in the regiments of killer-army white blood cells. And the more overwhelming the leaked toxin burden is, the longer the battle, and the greater the inflammation, not to mention red-hot pain.

Be under no illusion - leaky gut affects the whole process for just about every medical condition, be it joint, skin, brain - hooves especially as leaky gut is the main root source for laminitis. Everything depends on the integrity of that lining, which astonishingly is a mere 1-cell thick, so you can appreciate just how vulnerable the gut lining is.

Vaccines don't help either, as vaccines can contain proteins and other food particulates. This is because manufacturers use cells from animals, like chicken embryo and bovine serum, to grow the antigen. When the antigen finishes growing, they separate it from the protein, but sometimes small amounts can end up in the vaccine. During vaccination, these food proteins and other components get introduced into the body.

Cue an exaggerated immune response. All these components are identified as enemies, and when any enemy shows its ugly face, it’s time for battle.

These days we have the knowledge and the tools to get the diet right, not just in fibre but also in prebiotic fibre, which changes the microbiota for the better and nurtures it to flourish, in order to increase its production of the important byproducts the body needs to benefit health.

For our horses, it's fundamentally important that we look after their gut bacteria, and ultimately it's so simple to do. We need to feed the right stuff - species-appropriate food - to nurture our horse's microbiome, and avoid the bad stuff that feeds the bad bacteria. This is a whole separate chapter in itself - see our Feeding our Horses section, and specifically the Why what we feed has to be right page.

For the full story on leaky gut, see our separate chapters below - Leaky Gut - a Growing Epidemic.


- when we refer to ulcers, we're talking foregut ulcers. Hindgut 'ulcers' is a completely different thing; for starters they're a myth as there are no acid-secreting cells in the hindgut. If you've been given a 'hindgut ulcers' diagnosis, see our separate Ulcers link at the bottom of the page.

Here’s a thing – ulcers are there because the gut environment is already altered, usually due to either some form of stress, inappropriate feed, or stress caused by inappropriate feed.

Both these factors are the cause of why our horses – and us humans – get ulcers. Stress and/or the wrong food/food management destroy the gut environment, literally. Which means that without a strong, healthy protective mucosal gut lining, the foregut (stomach) acid will leak and create a wound, aka an ulcer, because it’s almighty strong hydrochloric acid in there, same as a car battery.

Some quick stomach acid facts:

  • Stomach acid is a prerequisite to healthy digestion – it’s there because it’s meant to be there. Without it, digestion will simply not occur. No digestion? No nutrient absorption.
  • If there isn’t enough acid, the normal chemical reactions required to absorb nutrients is impaired. No absorption? No health, full stop.

Sounds simple enough doesn’t it. Yet most of us have no idea how many vital roles the stomach acid plays in the body, whether horse or human, and ... the drug companies know it too. You can’t watch TV without seeing an advert for some chalky tablet to ‘calm’ the acid burn, especially after we've eaten a red hot curry.

The claim that the acid is causing the ulcers is a myth. The acid splash/leak is merely a side-effect of the stress/poor diet which has caused the damage in the gut.

  • Remove the stressors
  • Refocus on your training/discipline - considerate short bursts to allow your horse to process what you're trying to communicate
  • Switch feed to species-appropriate (see Why what we feed has to be right in our Feeding our Horses section)
  • Avoid any sweet feeds (Musli's/Beet) - it's what the pro-inflammatory gut microbes gorge on. which causes them to multiply and kill off the beneficial microbes that do all the good stuff like digestion
  • Avoid haylage (high lactic acid %)
  • Steam hay, don't soak it - soaking increases the bacterial content of hay
  • Make sure there’s continuous ad-lib forage
  • Let a horse be a horse, allowed to express their natural behaviour with freedom, buddies and social interaction - as the saying goes, 'Friends, Forage, Freedom'.

This isn't complicated - it's straightforward horsecare. Sadly we inherit a lot of damage when we take on a new horse so there's often a lot of unravelling and unpicking to do, but if you remind yourself that a horse is a horse (and not a cow, human or robot), and factor horse needs into your care, you'll very likely witness a remarkably quick, not to mention safe and natural recovery, without shovelling damaging symptom-blocking chemicals (PPIs - more on these in the dedicated Ulcers page below) into our horses' already altered - and damaged - digestive systems.

There's a really useful YouTube video to check if you think your horse is ulcerogenic - see the bottom of the page for the link.

Probiotics and Prebiotics

Despite the similarity in their names, probiotics and prebiotics are not just two different forms of the same supplement - they are actually two completely different types of digestive supplement with unique mechanisms of action on the gut.

Probiotics promote the colonisation of the beneficial microbes; prebiotics are the food that feed those beneficial microbes. Together they are fed to stimulate the growth and activity of the good bacteria that live in the horse’s gastrointestinal tract. It's exactly the same in the human world - plant/vegetable fibre is our finest prebiotic to feed our gut flora, so eat your greens, chop up an onion and grate yourself a carrot 😉

Back to our horses and my personal choice of probiotic? I feed Alltech's probiotic Yea-Sacc 1026, a live yeast culture based on the Saccharomyces cerevisiae strain, alongside Brewers Yeast as a general prebiotic, a highly nutritious non-active yeast providing (almost) the full compliment of B vitamins (with the exception of B12, although there's the tiniest trace). If ever there was dire digestive compromise or risk of, I'd add Alltech's BioMos as a prebiotic as it specifically binds to bad bacteria, e.g. salmonella/e.coli, and eliminates them.

We sell these items separately in our Individual Items section so you can add independently to the feedbowl. Look to add 2g/100kg bodyweight for YeaSacc, so for an average 500kg horse, add 10g. Brewers Yeast can be fed at around 20g daily/pony, 40g daily/horse. Alternatively, we combine them in EquiVita range of mineral balancers.

General pointers for a healthy gut system

  • Horses are herbivores and are designed to graze on a diverse range of fibrous, low-energy forages up to at least 20 hours per day - this forage needs to be diverse, i.e. a varied range of different grasses, plants, barks etc., to create a diverse microbiome. They should receive a minimum of 60% of their dry matter intake from good quality forage (e.g. hay, grass).
  • The best feed your horse can put in his mouth is grass. The second-best feed is hay, grass in its dried form. The bulk delivered by a fibrous grass/hay diet is a key weapon in avoiding colic because consistent gut-fill maintains a continuous level of digestive activity. Additionally, horses usually chew hay twice as long as grain. The more they chew, the more saliva is generated and mixed in, which helps buffer the GI tract against excess acidity.
  • Unfortunately, domesticated living usually challenges the horse's sensitive digestive tract with inappropriate processed feedstuffs, irregular feeding schedules and ration portions that are far outside the norm of the natural plan. One of the primary reasons that horses colic is the difference between what the digestive system is meant to process and what it actually gets.
  • Make changes in feed slowly over a period of 7-14 days and be careful about overfeeding manufactured feeds prior to an event.
  • Keep your horse moving – stabled horses are much more prone to gut issues than those who live out. Turnout with companions keeps horses happy, allows them social interaction and lets them eat their favourite food. Not only is the horse free to consume the ideal fibrous diet, but the simple, continual act of moving to eat, enhances motility of keeping the food moving along in the gut.

Top Tips

  • To promote healing of the gut, this is where the right kind of bacteria comes into play. The right kind of bacteria will break down fibre in the diet into molecules that are really easily used by the gut cells as energy sources. So other than making sure our horse has plenty of fibre and the right kind of bacteria in the gut to heal the gut, there are two essential amino acids you can use, especially if you're dealing with gastric ulcers or leaky gut. N-Acetyl L-Cysteine (NAC), the precursor to glutathione (arguably the most powerful antioxidant in the body) replenishes glutathione production. Glutamine is a building block for proteins that maintain cellular health and tissue repair. During critical illness, trauma, intestinal disease, excessive loss of lean body mass, and extreme endurance exercise, Glutamine is shown to be beneficial. Glutamine also works in synergy with NAC to help promote glutathione. We've blended both these amino acids together as a gut support in our GutAminos blend.
  • Aloe Vera juice can help support the stomach and colon. It's high in digestible fibre which gives it the properties of lowering bowel transit time, supporting hindgut bacteria, and soothing the digestive tract overall. Aloe also contains a complex mixture of mucopolysaccharides (complex sugars) that nourish cells and support them in replicating. Aloe vera juice is also especially important for gut acid; its polysaccharides can also be helpful for horses who have been on buffering agents that destroy the healthy bacterial populations in the gut and thus allow pathogenic bacteria to multiply. Good quality aloe juice can be found in most health food stores, and aloe concentrate powder is also available. Add 50-100ml of aloe to feed when your horse is displaying symptoms.
  • Slippery Elm v Marshmallow Slippery Elm is a renowned gut-healing herb with similar properties to Aloe. However, the native populations of the slippery elm tree are suffering due to its worldwide popularity and the tree is now considered extremely rare; as a result it's now a protected species which is reflected in its price - slippery elm isn't cheap. The good news is that the herb marshmallow can be suitably substituted for slippery elm because Marshmallow has almost identical properties and is so much more widely available - of course we supply both. Marshmallow root has a higher mucilage % than the leaf so is the better one to go for for gut soothing, with the leaf more indicated for respiratory tract soothing. Add 50ml Aloe and 1 desertspoon of marshmallow to feed.
  • Aloe and Marshmallow are not only beneficial for digestion in general but also support excess gut acidity as well. They can both be fed long term with no negative effects.
  • Apple Cider Vinegar is also invaluable for gut health - not only is it a beneficial supporter of immunity, it's also rich in natural probiotics, beneficial enzymes and acids that help absorption of nutrients.

"How to diagnose equine ulcers" - Mark DePaolo, DVM

Just 5-mins long, and shows the varying foregut ulcer symptoms in 3-horses – mild symptoms, then moderate, finishing with a horse with severe symptoms.

NB - ignore the recommended Omeprazole/PPI route at the end, and head to our dedicated Ulcers page below!