The Gut System

Content

Intro

1. All dis-ease begins in the gut
2. What destroys gut health?
3. How a horse eats
4. It's all about the forage - size matters!
5. How a horse does it naturally
6. The grinding/chewing
7. Digestion - it's all about the how
8. The foregut, and the vital role of the stomach acid
9. The rest of the journey
10. A quick intro to the all-important Microbiome, the body's 2nd Brain
11. The Hindgut Acidosis/Dysbiosis/SIBO/Leaky Gut/Autoimmune domino effect
12. Faecal water/diarrhoea
13. What's meant to happen
14. What actually happens
15. What acidifies the large intestine
16. How to check the intestinal values
17. The critical Gut:Liver:Kidney & B6 (P5P) connection
18. Could it be KPU?
19. Ulcers
20. Colic
21. General pointers for a healthy gut system

Sub-Chapters (links below)

- Colic

- Hindgut Acidosis - Lactic Acid/Leaky Gut

- The Microbiome

- Ulcers

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 waste.

Healthy digestion is about so much more than eating the right foods and making sure things are moving smoothly. For starters, around 70-80% of the immune cells are produced and housed in the gut. And you know that 'gut feeling' we all get? There's more to these than we think, because the gut and brain are actually connected by what's known as the gut:brain axis - what goes on in the mind literally transfers to the rest of the body, with negative thoughts provoking negative physical responses, with prolonged negative thinking eventually leading to chronic stress.

The brain can also impact the quality of the digestive tract lining and the release of chemicals into the digestive process. It's also the brain which controls the speed at which food moves through the digestive tract. Even certain neurotransmitters, like those associated with mood - think seratonin - are also produced in the gut.

Whether human or horse, caring for the digestive system should be a priority, as the overall health of the gut is going to influence everything, from behaviour, and how the body responds to stress and mood. Immune function may also be impacted, as specialised immune tissue called GALT (Gastric Associated Lymphoid Tissue) is found in the intestines. And no surprise, and my favourite subject - diet, which also plays an almighty huge role in gut (and thus brain) health. 

No doubt about it - the gut is doing a whole lot of important work that we're probably not even aware of. It's where every-thing starts. So let’s start at the beginning.

1. All dis-ease begins with the gut

So said Hippocrates, who was way ahead of his time because all these centuries later, science proves he was right all along. The digestive system is the Mother of all the body's systems, with the large intestine, aka the hindgut, the Mother of all the organs. But while everything starts with the gut, everything begins with the gut microbiome, and the entire gut - and thereafter the whole body's function, entirely depends on the healthy integrity of those friendly fibre-fermenting microbe colonies in the hindgut, who produce an amazing array of vital by-products - known as postbiotics and/or metabolites - which fuel both the horse's energy and the body's abiity to thrive.

The horse's hindgut region, which includes the colon and caecum, is the deciding point as to whether we have a healthy horse or not. Those friendly hindgut microbes - the biome that reside in the colon, normally tick along perfectly happily, fermenting all the lovely fibre from the stemmy grass forage (ideally hay) that the horse has eaten. However, if that delicate balance between friendly v. unfriendly microbes becomes disrupted, this will trigger a rapid overpopulation and colonisation of unfriendly acid-forming microorganisms, which forces a drop in the hindgut's pH level, creating an acidic environment referred to as hindgut acidosis.

And so begins the domino-effect of dysbiosis in the large intestine/hindgut, which if left unattended can lead to SIBO - small intestinal bacterial overgrowth. Hang on - small intestine, I hear you ask? 'Fraid so. If the population of the acidic unfriendlies overwhelm the large intestine (hindgut), they'll start to overflow and creep back up into the small intestine, which isn't good news at all, because the small intestine is meant to be mostly sterile (minus a small amount of beneficial bacteria) and needs to remain that way at a neutral, non-acidic, pH. If the unfriendlies move in and take over, they'll start fermenting the digesta in the small intestine, i.e. the sugars, starches and proteins. And when something ferments it creates gas, so the belly becomes bloated. In humans this is what causes IBS.

Worse, if this gaseous inflammation in the small intestine becomes pressurised (think of a balloon being pumped up), it can rip apart the very fragile intestinal wall. Cue what's known as leaky gut.

(Full disclosure - I should add that this lining can also break down from other factors, i.e stress, antibiotics, or NSAIDs such as bute and steroids, or a low-fibre/high-sugar diet, etc.  If you've ever had a vet say your horse has a gut yeast overgrowth or infection, as they sometimes like to call it, this is also triggered by these same factors, i.e. antibiotics, steroids, acid-blocking drugs, or a low-fibre/high sugar diet).

Now let's make matters more interesting. The small intestine is also the home of the gut immune system, which as mentioned earlier accounts for around 70-80% of the body's total immune cells. So, if we've got a leaky gut, we're now in real trouble because those unfriendly acidic, pro-inflammatory bacteria, along with particles of toxic undigested matter from the small intestine, will now leak into the bloodstream. This will wreak toxic havoc in the entire body, so the immunity activates an emergency red-alert response,  driving the immune system into a manic, panicked overdrive trying to control the situation.

Cue all kinds of gut issues and a tired/wired/foggy brain, along with other system-wide problems including allergies, arthritis, autoimmunity, mood disorders, colic, and the dreaded laminitis.

Welcome to the world of the equine gut system.

What destroy's gut health?

A healthy gut is the ultimate gatekeeper of good health, with a healthy microbiome the game-changer. It's been said in research terms that that this may very well be the decade, or even the century, of the microbiome.

The gut biome is probably the most important regulator of health; there are over 100-trillion gut microbes sending messages throughout the body, interacting with hormones, the immune system, brain chemistry, and every other system in the body. Yet when the gut biome's microbes are are out of balance, a malfunctioning body is the result. It really is as simple as that. Even in a perfect world, and whether human or horse, the gut has a hard enough time keeping things balanced, because in our modern world there are many things that knock the digestive system off balance.

Our modern day's domestic horse's digestive tract still looks exactly the same, and works exactly the same, as their ancestors' gut from millenia ago. The most common issue, however, is that us humans have taken our eyes off how we should be feeding our horses, and what should - and shouldn't - be passing through the intestinal tract. For the last half-century or so, we've believed the spin fed to us by animal feed producers, and instead of feeding our horses with what they're meant - and evolved - to eat, i.e. stemmy grass forage fibre, we've been duped by the feed-merchants shiny bags full of pro-inflammatory, gut-damaging junk food.

We need to go back to the classroom and relearn how a horse eats, and this is critical, because as our horses continue to tell us,  if we mess with this, it all goes horribly wrong. So, let's remind ourselves of how a horse is meant to eat.

2. How a horse eats

"Anything that's going on in the digestive tract is influenced by what you put in the digestive tract. You put the wrong fuel in a Ferrari and we know what's going to happen there."

Dr Tom O'Brien, Big Bold Health

The gut system isn't just a tube where food gets shovelled in one end and eventually bits of it comes out the other end. Well, it kind of is, but the whole gut system, from one end to the other and with all its integral parts, has a massive job to do in between.

First up, it's all about the forage, and trust me - size matters

It all starts with the initial chewing process, which mechanically breaks down the forage (to expose the fibre within) into tiny pieces of between 2-5mm. Yes you read that right. Millimetres. This length is vitally important as the entire process of digestion, including peristalsis motility, takes place through a very long, and very thin, tube - meet the small intestion. From start to finish, an effective, successful digestion process is entirely governed by the length of those chewed and ground-down forage fibres.

So now let's cast our mind to chaffs, some of which present a potential problem because the forage used is generally cut to longer lengths of around 5cm - that's centimetres - with some even longer, which horses can't thoroughly chew as they're too short; think of the grass lengths they rip off with their teeth - they're at least 10-20cm long, and this is the ideal length for the back molars to grind down. This means that a chaff of around 5cm won't be adequately ground down, so they remain too long to be properly digested. The horse then swallows these too-long fibres, which then alters peristalsis motility, the end result being that these too-long fibres can remain festering in the colon for up to a week. An obvious sign is if your horse's droppings are a bit whiffy, or smell 'rotten'.

This can then lead to a gut-disruptive cascade, various metabolic disorders, or worse, colic.

Now, before everyone gets their rulers out, I completely get that it's nigh on impossible to find a chaff made from tiny cut fibres, so my own personal take on this is not to get too anal about it. I personally can't find a chaff that's cut less than 2mm (virtual dust) or greater than 5cm, that follows my own personal ethos of organic, diverse multi-grass species, but there's also a very simple solution to this. Don't feed a chaff. Seriously. Our horse doesn't need a chaff, or rather, the feedbowl doesn't need a ton of different 'stuff' in it. All it needs is an appropriate meadow grass 'cob' that soaks down into the perfect size pieces. Job done.

Edited to add (Sept'22) - I've since found the Agrobs' Senior Chaff is cut near as damnit to the perfect length, and because my ancient connie, Murf, lost a tooth this year with his others described as 'worn', he's going to stay on this forever now as his feedbowl carrier. Quick tip - feeding a meadow hay cob (Agrobs, Thunderbrooks, Baileys all do really decent ones), also soak down to the 2mm size.

Back to chaff and ideally, the optimal chaff fibre length is around 10cm minimum, which to the naked human eye is pretty long, but this is the minimum length that will encourage a horse to chew what's in their feedbowl, instead of inhaling it. For the record we've heard of dramatic improvements in gut health when clients have sourced a more appropriate chaff, or fed a meadow hay cob, while ensuring adlib hay features as the main grass forage.

How a horse does it naturally

In a natural environment of free-growing long, stemmy grasses (not what we generally have here in the UK), the horse will tear the perfect size mouthful with their front teeth, then ‘roll’ it into the toothless gap where we put the bit. This is a tasting area - horses are very particular about what they eat as, once they've committed to chew and then swallow, this means the job's done, ready for the huge process of digestion. And reminder - unlike us humans or dogs, horses don't have the luxury of being able to vomit anything nasty back up, so this tasting area allows them to sort out any toxic plant and spit it out to the side, because once it's swallowed, there's no going back.

The grinding/chewing ...

Once they’re happy with the taste, they roll the forage into a ball - the 'hay roll', and here’s where the grinding of the forage takes place, to break down the grass stem wall and expose the inner cellulose/hemicellose fibre that the hindgut microbes will then break down to produce the horse's energy. Grind grind grind, until it’s all broken down to 2-5mm pieces, ready to be swallowed. This grinding/chewing also initiates saliva to be produced which adds moisture and mucus to the mix, as well as bicarb which starts to regulate the oesophageal pH level.

Daily trivia - did you know? To chew 1kg of hay takes up to 3,500 chewing motions over 40-50 minutes,
and generates 3-5 litres of saliva!

And here’s where the fibre length is so important – the forage length needs to be 10cm or longer to be chewed properly, or less than 5mm so it can be automatically swallowed. If it’s in between these numbers the horse won’t grind it properly, so we risk unchewed fibres sitting in the hindgut for longer and fermenting/rotting, because the inner cellulose fibre won’t have been exposed by the teeth grinding apart the forage stem. Hence why, when it comes to chaffs or hay, it's useful to be mindful of the fibre length.

Back to it, and once the grinding/chewing's done, the horse is now ready to swallow and pass the ground 'bolus' into the oesophagus. The oesophagus is is like a garden hose, around 1.5-meters long in an average horse, but only around a very narrow 1.5-cm wide, so you can see how each bolus has to be ground down very finely to then pass through this very narrow tube.

*Choke Alert - if the food isn't chewed small enough, this can also make horses prone to choking. We know that horses don't generally chew the contents of their feed bucket slowly so it's all the more important to be aware of the particle sizes, especially if you're also including chopped pieces of carrot or apple. Always ensure these are chopped into tiny pieces because if they're not chewed properly they can get stuck at the bottom of the oesophagus, being too large to pass through the sphincter entrance to the stomach/foregut.

3. Digestion - it's all about the how

So, the chewed food bolus has now merrily moved down the oesophagus and now passes into the stomach/foregut. Certain digestive enzymes now begin the protein and starch pre-digestion process, and the stomach muscle wall begins churning like a washing machine, breaking down and liquifying the bolus even further before it's then 'disinfected' by the stomach acid and turned into a soupy mix, chyme. It now passes easily into the small intestine (SI). 

The main digestive process now starts. Proteins, starches, carbs, and fats (EFAs, i.e. Omega-3) are digested, while the micronutrients (vitamins, minerals, amino acids) are assimilated so they can be absorbed into the bloodstream to fuel the body. What's left at the end of the sorting process - forage/roughage fibre - continues onwards to the large intestine/hindgut, where the hindgut's friendly fibre-fermenting microbes set to work on the fibre and produce vital metabolites (postbiotics) such as some vitamins and amino acids, and the all-important SCFAs (short-chain fatty acids) for the horse's energy production. The resulting waste becomes 50% fibre/50% micro-organisms, eventually shifting onwards to the main elimination exit point and coming out as perfect poo parcels 😉.

The small intestinal tube doesn't do all this by itself - the very function of the gut system relies entirely upon it's own army of elements. The SI digestion operates via enzymes with most (over 50%) of the protein pre-digestion and most of the soluble carbohydrate pre-digestion happening in the stomach. Fats are then broken down in the small intestine by bile, ahead of the hindgut, which is where we'll find the cecum and two colons, and this is where it's now all about the bacterial, aka 'microbial', fermentation of the fibre forage sources, i.e. grass, hay, and woody (lignan) fibres. And because our horses' energy comes solely from the hindgut fibre fermentation byproducts, it's our job to ensure that the hindgut's friendly commensal bacteria/flora/biota remains well-populated, right up there at the top of the list of priorities.

Horses normally consume 2-2.5% of their body weight in dry fibre matter each day, although if they’re on grass pasture 24/7, this can go up to over 3%. Remarkably, the capacity of the stomach of the horse is small, about the size of a rugby ball and coming in at just 8-15-litres depending on the 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 time it takes for food to transit from the stomach to the small intestine is anywhere between 2-6hrs, and it never empties - in fact, the stomach should never become empty. There's a reason a horse is a 'trickle feeder' - this is so important as so many equine health issues are caused through us as their carers not providing enough forage when stabled, meaning the stomach becomes empty. Cue squamous ulceration.

As the horse continues to eat, the digesta trickles through into the small intestine, hence the term ‘trickle feeders’. The rate of passage through the small intestine is about 1-ft/minute, with the average length in total of the small intestine being a whopping 70-feet (apx).

The foregut

The foregut is the only part of the gut system that's meant to be acidic. Once digesta moves into the small intestine and onwards, the intestines require a neutral pH. It's a huge problem if the intestines and onwards becomes acidic, which these days is very common and a major contributor to gut issues. More on this as we go.

The stomach acid is there for a massively important reason, well, two actually. Firstly, it's there to kill off contamination that's come in on the forage. Stomach acidity is the bodies’ first defence against harmful bacteria, so here's a thing relating to stomach ulcers - if we suppress the production of acid with PPIs (proton pump inhibitors), aka any of the ulcer pharma drugs ending in 'zole', we're letting harmful contaminants straight through into the intestines, which will only damage the gut biome, but also wreak havoc on the digestive process, particularly impaired protein digestion.

When undigested proteins pass into the hindgut, the horse is in real trouble. Tim Spector, an epidemiologist best known for leading the Zoe Health Study, states that studies have shown Omeprazole “changes the microbiome for the worse”, increasing the risk of gastrointestinal 'infections'.  Stopping taking Omeprazole can even result in more issues than taking it, as the body becomes reliant on it, so the symptoms actually get worse afterwards. For the full grim story, see our separate Ulcers page.

The second reason why the stomach acid's role is so vital, is that it activates the protein digestive enzyme, pepsinase, into pepsin, without which, those proteins won't get digested.

Back to the foregut and the pre-digesting of the foodstuff, and it does it via 3-sections:

• The first section, the pars nonglandularis, has a reasonably high pH, between 5-6 - there's no stomach acid in the front section of the foregut, but what we do have here is resident lactic-acid bacteria (LA), usually brought in by the horse ingesting it from their feed/forage. STOP PRESS!! Under normal circumstances the last thing we want anywhere in the intestines is lactic-acid bacteria, but in this front section of the stomach it's expected, and the good news is that at least here in the front section of the foregut these usually unwelcome acidic bacterial actually have a useful job to do.
  
  LA bacteria produce lactic-acid from eating starch and sugar in the feed - it's where they derive their energy from as they can't utilise plant fibres. So, when the horse has ingested starches, lactic-acid bacteria in the pars nonglandularis start pre-digesting the starch molecules which makes them easier for the small intestine to digest further on.
  
  Note: this is also the region where the horse experiences squamous ulcers, caused by inappropriate feed or when the stomach has been allowed to empty, i.e. not enough hay in the stable).
  
  Further Note: don't be misled by thinking LA bacteria are friendly as they're really not - if they manage to slip through into the intestines, this is bad news - see our separate page on Hindgut Acidosis (link also below).

• Now to the stomach's middle section, and this is where the pepsinase enzyme, the protein digester, is produced - this is then activated into pepsin in the stomach's back section by the stomach acid to perform the protein pre-digesting - see next para. This activation can only happen when the stomach pH drops to below 4, when the digesta hits the hydrochloric acid in the back section of the stomach.

• Now to the stomach's back section, the pars glandularis, where the hydrochloric acid sits - its role is basically to disinfect any nasties in the feed such as microbial contamination. A bit of quick trivia digress - this is how dogs survive eating other dogs' poop, as well as other revolting rotting foodstuffs, because their acid pH value is at a super-severe 1!. This is also where, as mentioned above, the protein digestive enzyme, pepsinase, is activated into pepsin, and can now start to degrade the proteins in the feed. Horses generally have a hydrochloric acid pH of around 3 - less harsh than a dog or cat - to reduce the level of microbial contamination in the feed.
  
  Note: this is also the region where the horse experiences glandular,akapyloriculcers caused by stress resulting in poor blood flow, which when healthy, normally produces the protective mucus layer on the mucosa membrane. Again explained in full in our Ulcers page.

In summary, here's the normal foregut process :

• Ensure a horse has a constant uptake of forage fibre so the stomach remains constantly full, preventing acid splash burn.
• Pre-digestion of starches occurs via LA bacteria in the first section.
• Pepsinase production occurs in the middle section.
• The back section activates pepsinase to pepsin, alongside inactivation of any remaining LA bacteria and microbial decontamination on the feed.

Once done, the pre-digested starches and proteins, along with the decontaminated fibre matter etc., are now ready to exit the stomach and head into the small intestine.

The rest of the journey

Once the digesta hits the small intestine, a bile trickle is released from the liver to digest the EFA fats (the omegas) from the forage, while the nutrients in the digesta are assimilated ready for absorption into the bloodstream. Along the way there have been fluids and mucus to lubricate and keep everything moving. Finally we get to the hindgut, where the fibre is fermented down by the hindgut's own friendly fermenting microbes, and this is where the horse's energy is produced.

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 them it won't be able to digest the food or supplements that we pay good money to keep our horses healthy.

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 feed the good bugs and starve the bad bugs - this is critical for maintaining that healthy environment and preventing SIBO, which as mentioned earlier can lead to leaky gut syndrome if left untreated; for the record this is now so widespread that it's now considered an epidemic, and all because of the way we feed them. See our Blog Post on The Misery of SIBO for the bigger picture.

To summarise, if you're looking to clear up chronic symptoms that may be chipping away at your horse's quality of life, there's only way to do it - feed a constant supply of quality, high-fibre, grass forage (hay)and roughage - barks, woods, leaves, berries and roots, ideally found through natural browsing - which add valuable prebiotic diversity food for the hindgut microbes to chow down on - see our WildFed.

Note:. The foal is born with a sterile gut, so as they grow, they're slowly creating their biome, with a fairly undeveloped caecal and colonic digestion compared to the adult horse during their early years. 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 (coprophagia) are endeavouring to acquire a healthy bacterial culture for future microbial digestion, so if you see this happening, encourage it! See our separate chapter in this section The Foal's Microbiome - setting up a foal for life.

4. A quick intro to the all-important Microbiome, the body's 2nd Brain

Due to the obsessively sanitary nature of modern existence, bacteria’s got a bad reputation. However, these bugs in our gut microbiome actually do a huge job - not only do they help digest food and assimilate the nutrients for absorption, but they regulate our immune system, improve our mood, stabilise weight and remove environmental toxins.

Focusing on improving gut health by nurturing the friendly bacteria is key to achieving both optimal physical and mental health, because gut health IS health.

Collectively the beneficial friendly and unfriendly microbes outnumber the regular cells in the whole body, by an astonishing 10-1 at least!. Think about that for a second - that's a whopping 10-times more bugs in the GI tract - that long tube from mouth to the final exit point - than in the whole of the rest of the physical body. Tis true - we're all more bug that horse or human! Which means - if the microbiome gets disrupted, we're in a whole lot of trouble.

So, looking after our horse's gut microbiome by feeding it what it needs and is meant to be fed - course, stemmy, cellulose-rich fibrous hay - 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, crucial to fuel a healthy body. But it's so much bigger than this - the microbiome is the body's CPU - it literally runs the show. With the majority of the immune cells created by the gut microbes and housed  in the intestinal tract, these microbes are also the major regulator of the immune system. The difference between healthy and unhealthy relies entirely upon the gut microbiome's performance.

There's always a downside though. There are certain medical protocols which can really mess with the gut ecology, such as antibiotics, bute, PPIs, chemical wormers ... all disrupting 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 completely wipe out the gut bacteria, the bad bugs as well as the good bugs thatthe body can’t live without. Feeding activated charcoal will also have this effect as well because the charcoal doesn't discriminate between good and bad bacteria; all well and good if you're having your stomach pumped in A&E, but not so great if you're trying to shift just the bad stuff out.

A healthy microbiome will also significantly minimise the laminitis/colic risk, and protect the horse against infections such as diarrhoea-causing organisms like salmonella or clostridium.

There is good news though. A healthy, functioning digestive system is really straightforward to manage. It really is! Provided ... we feed them what a horse is meant to eat, and not pro-inflammatory gut-damaging food. And two things you can immediately address is 1) cheap feedbags full of bulk-fillers with barely a hint of grass-forage fibre in - see our Feeding our Horses Healthy section in the Advice Centre on the main navigation bar. And 2) feed hay, not haylage.

The equine digestive system is extremely sensitive; it doesn't take much to upset the delicate gut ecology and 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 - The Microbiome - the Missing Organ? I promise you it's an eye-opening read ...

5. The Hindgut Acidosis / Dysbiosis / SIBO / Leaky Gut /Faecal water domino effect

“Dysbiosis (also called dysbacteriosis) is a term for a microbial imbalance or maladaptation on, or inside, the body, such as an impaired microbiota.”
Wiki

Also known as faulty (hindgut) fermentation. And alongside metabolic issues, the hindgut is right up there at the top of our client enquiries. Time and time again, our clients' horses are struggling because their horses' hindguts are in trouble. Thing is, hindgut issues affect the whole body, because the fragile intestinal barrier is a gateway to the systemic immune system and the enteric nervous system, connecting to the brain via the bloodstream and vagus nerve - the gut:brain axis, which in short means that when issues linger in the gut for a prolonged period of time, they show up in various other forms throughout the rest of the body too. And it all starts with dysbiosis in the hindgut microbiome.

Microbiome dysbiosis is when that very delicate microbe balance within the gut biome environment is disturbed, and the balance between friendly and unfriendly microbes becomes disrupted. Cue a fault in the vital fibre fermentation process, which is crucial as a horse is nothing more, and nothing less, than a grass-forage cellulose fibre-fermenting machine. They're literally evolved to eat grass forage fibre, and little else.

We also know that the intestinal lining is supposed to be strong and tight, keeping digesta, microbes and waste safely inside the digestive tract. So why is dysbiosis, SIBO, leaky gut, and faecal water syndrome now becoming an epidemic?

As the saying goes, 'Everything starts with the gut,' but when it comes to dysbiosis, everything begins with the biome. I can't stress enough how important it is to centre our attention on the microbiome, and specifically those beneficial gut microbes, in order to avoid dysbiosis. Another fact - it's the microbiome, as in a healthy, optimally functioning hindgut biome, filled with lots of happy, beneficial microbes busying away and fermenting the fibre to produce those vital byproducts - metabolites - that enable our horse to function and thrive, that regulates the permeability, aka leakiness, of the gut wall lining. This is the connecting factor.

When the hindgut's fibre-fermenting bacteria colonies are disrupted and the bad bugs outnumber the good, those bad bugs set up camp and create gaseous inflammation. When inflamed to the point of bursting, the pressure then tears apart the tight junctions of the gut wall which makes it permeable, as in leaky, and allows the undigested, putrefactive toxic content in the small intestine to leak through the gut wall and into the bloodstream, literally poisoning it.

This then triggers an almighty inflammatory autoimmune cascade as the immune system goes into hyper-overdrive, desperately trying to seek and destroy those leaked toxins.

Cue the battlefield. Getting a bit science-y now, but special antibodies, aka immunoglobulins, 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. 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 causes laminitis. Every-thing depends on the integrity of that gut wall membrane, which astonishingly is a mere 1-cell thick, so you can appreciate just how vulnerable the gut lining is. More on leaky gut in our Blog Leaky Gut - a new epidemic?

(Note: Vaccines don't help either, as vaccines contain unfriendly proteins and other food particulates that have no place in the equine body. This is because vax producers use cells from animals, like chicken embryo and bovine serum (amongst others too disgusting to mention), to grow the antigen - a substance that causes the body to produce an immune response against it. When the antigen finishes growing, it's separated from the proteins, but sometimes small amounts still end up in the vaccine. During vaccination, these food proteins and other components get introduced into the body. Cue yet another exaggerated immune response. All these components are identified as enemies, and when any enemy shows its face, it’s time for battle.)

The thing is, when we've got leaky gut, we've also got faecal water.

6. Faecal water/diarrhoea

Any metabolic gut disturbances, i.e. diarrhoea/faecal water, are all signs of dysbiosis in the hindgut, and it’s becoming more and more common these days because so many horses' gut systems are in a state of dis-eae, usually due to poor feed practices and/or ongoing chronic stress.

Of course no-one plans to feed their horses inappropriately or cause them harm - the vet bills alone are enough to put us off. However, there's so much spin and misinformation out there on those shiny bags in the feed merchants, that these days it's all too easy to get it wrong. That's why we're here to untangle the BS, so let's deconstruct this syndrome to understand it better.

What's meant to happen

During normal digestion, the resulting waste is formed into faeces, becoming thicker and forming into the round balls that we’re all familiar with, due to the peristaltic movement of the intestinal muscles. However, if the horse is suffering from faecal water, the faeces are excreted as a brown fluid, either in drops or a whole stream of fluid, sometimes projectile (this was my connie, Murphy, when he'd been let loose on haylage). Faecal water can also occur in specific situations – for example, if the horse is under stress.

What actually happens

The large intestine (hindgut) depends on a very precise neutral pH value for the friendly fibre-fermenting microbes to survive; in a healthy horse, this value is between 6.8 and 7.2 (neutral range). However, if that neutral value drops to a lower, acidic pH value below 6.8, this will kill off the friendlies.

The acid also harms the intestinal mucosa, which consequently becomes inflamed. In the long-term, this inflammation causes the dense cell structure lining of the intestines to loosen, creating leaks, aka leaky gut syndrome. This causes the faecal water to become self-perpetuating, as the absorbed fluid is able to flow back through the leaks into the intestine, but cannot be sufficiently absorbed again, so is excreted. This leads to what we see as visible faecal water.

With faecal water, the fluid is extracted from the faeces then flows in the wrong direction, back into the intestine. Faecal water is derived from an acidic environent so is itself highly acidic, which, in turn, causes further inflammation of the intestinal mucosa. Faecal water itself, therefore, ensures that more faecal water develops through its self-perpetuating cycle.

This also occurs for horses that only have faecal water in specific situations, like stress. Even the slightest disturbance in the function of the intestine and blood circulation, all of which have a sensitive symbiotic relationship, causes an imbalance, enough to trigger faecal water.

What acidifies the large intestine?

The combination of acidic feed (haylage) and lactic-acid bacteria which either finds its way in or those horses fed with lactobacillus and ‘bifido’ probiotic cultures, have a detrimental effect on the horse’s intestine. As we repeatedly mention on this website, lactic-acid bacteria are absolutely not a welcome member of the horse’s natural intestinal flora; these bacteria prefer pH levels below 6, which is way too low for the horse’s intestinal environment, so if they're surviving in the intestines, the intestines are too acidic.

Lactic acid bacteria break down the proteins and sugars found in roughage, but not the structural carbohydrates. Unlike the friendly fibre-fermenting biota, they don't produce the vital metabolite molecules which the horse uses energy production. Instead, they continue to multiply, as bacteria do, which further acidifies the intestines, strengthening and increasing the lactic-acid bacteria colonies. The result? They become the dominant gut biome colonies as the beneficial gut microbes are simply unable to survive in an acidic environment. We now have significant hindgut dysbiosis and faulty fermentation.

How to check the intestinal values

pH value

6.8 – 7.2 = normal (neutral) range

< 6.5 = acidic

< 6.2 = very acidic

Indican value

The Indican value is found in urine samples. It indicates faulty fermentation in the intestine, which, if found, must be treated even if there are no visible signs of faecal water.

Indican 0 = no findings

Indican 1 = slight rotting

Indican 2-4 = severe, and often long-lasting, intestinal putrefaction (the process of decay)

7. The critical Gut:Liver:Kidney connection (and Vit.B6)

If there’s something leaky going on, this is also going to have a profound knock-on effect on the liver/kidneys detoxification function, because when there’s leaky gut, there’s an overload of toxins in the bloodstream which the liver has to rapidly metabolise (correct name biotransform).

Thing is, the kidneys are very much involved as well because the liver shunts all the transformed water-soluble toxins to the kidneys for excretion (the fat solubles are sent back to the large intestine to join the solid waste). However, if there's a huge queue of toxins waiting to be excreted, the kidneys become overwhelmed as well as they simply can’t shift all the toxins out quickly enough via the urine.

Result? These toxins get recirculated back into the bloodstream around the body, and are either sent out via the emergency excretion route – the skin (hence why horses can suddenly get unexplained itchy/crusty skin for no apparent reason), or they’re sent off to the soft tissue for storage, and yes we're talking tendons/ligaments/muscles. This can explain why there’s sudden ‘skin’ tenderness or inflammation - swollen sheaths are a classic example, or unexplained tendon/ligament/muscle issues where the toxins have taken up residence.

Of course, as science would have it, it’s a whole lot more complex than this! But at the very root of the problem lies a tiny, yet critical, micronutrient - vitamin B6. But not just any old B6. We're talking activated B6 - Pyridoxal-5-Phosphate, nickname P5P, and not to be confused with Pyridoxine, the synthetic off-the-shelf form that we find in most equine vitamin supplements. The equine liver doesn't recognise or knows what to do with Pyridoxine, so shunts it straight out to the kidneys for excretion. (As the saying goes, 'An expensive way to make urine'. Seriously, save your money, as well as the extra strain on your horse's liver and kidneys).

Back to P5P, and here's a major thing; only the friendly hindgut fibre-fermenters can produce P5P. Remember those vital hindgut-produced byproduct metabolites? P5P is one of them.  And here's why it's so important.

When the hindgut microbiome is in the throes of dysbiosis, the activated B6 ‘P5P’ production becomes deficient, and here’s where it all goes badly wrong because … the liver absolutely needs this critical B6 activated form - P5P – to break down / metabolise / biotransform – toxins. Which means, if the liver and kidneys can’t do their job properly, the whole natural, in-build detoxification process gets badly messed up.

Since 2021, this is now known to be very much connected to a now widespread multi-metabolic detoxification disorder called Cryptopyrroluria, aka KPU. This knowledge is proving to be the missing jigsaw piece of a huge range of metabolic disorders that owners have previously struggled with, unable to get to the bottom of, despite throwing every kitchen sink and their last coppers at. And all because P5P wasn't being produced by the hindgut microbes.

Of course, as with all science, it's a much bigger picture than just a missing vitamin. But in short, and without getting too science-y, not only is there the toxicity overload, but these toxins are also damaged, dangerous, and putrefactive (relating to or causing decay), because the liver hasn’t been able to break them down properly, hence why the presenting symptoms and issues can be such a profound, long-term, chronic nightmare.

You’ll usually know if your horse has developed a multi-metabolic disorder by the presenting symptoms, and there’s usually a multitude of them, everything from continuous gut disturbance, skin problems, hoof issues, unexplained tendon/ligament injury, musculoskeletal issues, chronic ongoing cough/wheezing, mallenders/sallenders ... even headshaking’s now on the list, and of course we can’t forget EMS. Basically it can lead to a whole range of symptoms continually shifting around the body which here at EquiNatural we see repeatedly, where ‘everything’s wrong’.

If this is the case it's likely that a hindgut:P5P:liver:kidneys restoration programme is needed, all of which we covere in full detail in our KPU page. The good news? Since 2021 we've put together a full KPU regeneration programme which has proved a godsend to horse owners, including us with our MacAttack pony who was also a classic KPU candidate.

These days we have the knowledge and the tools to get the equine diet right - grass forage fibre and roughage prebiotics all the way to feed and nurture the hindgut biome, so it flourishes and produces all those vital metabolites/postbiotics that the body needs. See our Blog Prebiotic Foods for Postbiotic Abundance for more on this particular story.

So here's a perfect place to link onwards - what if it is KPU?

8. Could it be KPU?

So, we know that many essential metabolite nutrients are produced by the hindgut biome, known as postbiotics, which include several amino acids, vit.K, vit.B12, and the aforemented critical B6/P5P for the liver biotransformation process. If faecal water has been profound and prolonged, there’s every chance that the disruption is significant enough to have affected liver function, which may be a whole other complex issue called Cryptopyrroluria, aka KPU for short, which is very much connected to the gut:liver:kidneys pathway, ultimately affecting the immune system as well.

(It's well worth a read of our KPU page for the full story, as well as a list of all the typical symptoms which these days are very common and well recognised, and for an affected horse this could literally have started from birth.)

Long and short, this dysfunction underlies many of the well-known metabolic diseases we see; in hooves it manifests as poor hoof quality, thrush, WLD, frequent abscessing, permanently footy. It can also trigger laminitis, recurrent colic, a constant chronic cough, sweet itch, mallenders/sallenders, persistent diarrhea, loss of performance – even headshaking’s been associated with it …

As at 2020/2021 KPU is slowly being understood as a stealth problem behind so many of our horses’ issues today, and one of the reasons why so many horses are continually sick, the owners barely getting getting on top of one issue before something else occurs, despite their heroic efforts.

Whether it's KPU or not, basically, when there's faecal water it's imperative to regenerate the hindgut biome, and then get the liver working properly again. Coarse stemmy hay is going to be your saviour here – absolutely not haylage as this creates lactic-acid in the hindgut, nor our neon-green grass as this is just high-starch/sugar leaf with no stemmy fibre, and also full of pectins which also create lactic-acid in the hindgut. With a horse being nothing more - and nothing less - than a hindgut fibre fermenter, we need to get those all-important equine-appropriate grass forage plant fibres, cellulose and hemicellulose, found only in long, dry, growing grasses or stemmy hay, permanently passing through the hindgut to rebalance the biome.

If haylage has been fed, the gut also needs to deacidify, so we need to feed Spirulina. Spirulina has proven itself in being fed to our horses for many years with its detoxifying properties; it's an an excellent toxin-binder supporting intestinal biome balance, and is mainly excreted via the liver-bile-intestine, thus relieving the kidneys. It also has a high protein content with a very good amino acid pattern for horses, and a high content of vitamin B12 as well.

Spirulina is also useful to feed during each coat change, which puts extra biotransformation pressure on the liver and kidneys - see our Coat&Skin page for more info on this.

Meanwhile ...

• No beet, no alfalfa, no sugars, no pectins, no muslis, no pellets, no treats, and definitely no feedbags with wheatfeed, oatfeed, soya, NIS in any form for at least 6-months, basically anything listed in our ‘The Feedbowl – what’s really in those feedbags’ page. The more grass-forage fibre the feed regime is, both feedbowl and forage – in other words, the more species-appropriate, as in what a horse is meant to eat and what a horse’s gut is meant to digest – the faster the hindgut environment will be restored to normal.

• Now we need to clean up the gut, liver and kidney function. We start with clearing up the dysbiosis and a 1-month course of our SiboCare blend, alongside repairing the gut membrane with our GutAminos.

• Leaky gut/SIBO hurts - you would have likely seen gut flinching, biting, head swinging back to the hindgut, maybe even cow-kicking. In extreme cases, alleviate with our TriBute for 7-days alongside our SiboCARE, then continue with our DuoBute.

• Meanwhile, we need to feed the activated form of vitamin B6 - Pyridoxal-5-Phosphate, aka P5P, to kickstart the liver repair - we sell it in human-grade powdered form.

• When the gut regeneration is done, take a 1-week break before we start on the liver/kidney function. Feed our LKLCARE for 1-month (1kg), and if your horse doesn't have access to natural browsing, i.e. trees, leaves, lichen, barks, berries, fruits, maybe have a look at our WildFed mix as it’s vital to support the horse's natural eating behaviour.

Top Tips

• The first thing to do is check what you’re feeding, as any feed or ingredient that can disturb the friendly gut microbes should be replaced asap with grass forage fibre, i.e. quality hay.

• Avoid anything sugar - in addition to haylage, the intestinal flora is adversely affected by any feed that contains sugar. This means no carrots, apples, mueslis, or any feeds that contain molasses or apple pectin/pomace, so always check your feedbag ingredients. For the record, beet is an issue here - unmolassed beet still contains up to 7% sugar residue, with the molassed beets up to 25%.  Full disclosure - this one hurts as I like to give my horses a bit of carrot each day as bribery, and hands in the air I still do, but only a couple of pieces, followed by a few grass cobs.

• Essential meds only – always be mindful of what meds you may be feeding, including wormers, as it's a given that they'll upset the gut biome, never mind the liver. Only worm if you know your horse has a known worm infestation following an FEC, and not simply as a precautionary measure.

• Avoid empty feed periods of more than four hours as this leads to a breakdown of the intestinal biome. Always ensure adlib hay is available, and if you can, provide access to roughage as well – barks, roots, twigs, leaves. Sainfoin (Simple Systems) can also be beneficial for horses with gastrointestinal sensitivities as it's high in tannins which maintain a friendly gut environment for the good gut bugs, while being hostile to the unfriendlies.

• Psyllium husks are a life-saver to help mop up the excess faecal water - feed 20g/day for at least 2-wks.

• Spirulina helps stabilise the pH level while effectively relieving excess toxins. Again feed 5g/100kg bodyweight for at least 2-wks, every couple of months or so.

Meanwhile, back to dysbiosis/biome disturbance, and here's one we've all no doubt had to deal with at one time or another ...

9. Ulcers

* When we refer to ulcers, we're talking stomach/foregut ulcers. If you've been told your horse has hindgut 'ulcers', this is a myth - they don't exist because there are no acid-secreting cells in the hindgut. There is, however, hindgut acidosis, as mentioned above, caused by lactic-acid being present in the hindgut and lowering the pH value to acidic.

FACT - Squamous gastric ulcers occur when the stomach acid come into contact with the mucosal wall of the upper stomach, known as the squamous region. This region does not have a protective mucus layer, iunlike that found in the lower, glandular region, where the acid is secreted. Note: Glandular/pyloric ulcers are caused by stress, resulting in a poorer blood supply - see our Ulcers page for the full explanation.

This means that stomach/foregut ulcers happen because something's changed in how our horse is meant to - or has been able to - feed. This may be due to lack of forage, stressors (or stress caused by lack of forage), or pharma meds which alter the stomach environment, weakening the integrity of the protective mucosal lining on the stomach wall, causing the stomach acid to then splash onto the exposed lining and create an ulcerated sore. This is why our horses – and us humans – get ulcers.

Sounds straightforward enough, doesn’t it. And the drug companies know it too, especially for us humans - these days you can’t watch TV without seeing an advert for some chalky tablet to ‘calm’ an acid burn, especially after we've eaten a red hot curry. In our minds it's the stomach acid that becomes the enemy, the 'cause' of those ulcers, but this couldn't be more wrong - the acid splash is merely a symptom of the gut-altered environment due to something we've done, or eaten, in the first place.

The reality? Stomach acid is absolutely integral - vital - to healthy gut function and overall health, yet most of us have no idea how many vital roles it plays in the body, whether horse or human. Sadly many of us inherit a whole lot of issues when we take on a new horse, especially an ex-racer, so there's often a lot of unravelling to do, but if you remind yourself that a horse is a horse, and not a cow, pig, sheep, goat, dog, human or robot, and factor specific equine management as your care protocol, i.e. friends, forage, freedom, you'll very likely witness a remarkably quick, not to mention a safe and natural recovery.

See our separate chapter on equine gastric ulcers, link below.

10. Colic

Colic is the one issue that I’ll call a vet for. It can strike any horse at any time, and nothing in any herbal cupboard will help a horse quicker than a vet’s injectable toolkit. That said, once a horse is recovering, herbal support can be immensely supportive.

Put simply, colic is due to a major disturbance in the gut system's intestinal region. Anything from bloating, massively disturbed peristalsis, constipation, abdominal spasming, or positional changes where parts of the intestine are no longer where they belong, and can therefore be cut off from the blood supply, are all typical reasons behind a colic episode.

Unfortunately, when colic hits, we can’t always tell what the trigger was, and how your horse presents also says nothing about the cause or severity. Hence why we should always call the vet immediately – every second may count, and far better to pay for a false alarm than overlook a severe colic.

See our separate chapter on colic, link below.

11. General pointers for a healthy gut system

• Horses are herbivores which evolution has designed to graze on a diverse range of high fibrous, low-energy forages up to at least 20 hours per day. In the perfect world this forage should consist of multiple diverse grasses, plants, barks, roots etc., to create a diverse microbiome.
• Here In the UK the best feed your horse can put in his mouth is hay - grass in its dried form. The bulk delivered by a fibrous hay diet is a key weapon in avoiding colic because consistent gut-fill maintains a continuous level of digestive activity.
• Allowing your horse's stomach to become empty is one of the biggest causes of stomach ulcers, so always make sure hay is fed ad-lib. It's just bonkers to ever let your horse run out of forage.
• The more a horse chews, the more alkaline saliva is generated and mixed in with the mouthful of hay, which helps buffer GI tract acidity.
• Steam hay, don't soak it - soaking increases the bacterial content of hay.
• Don't feed haylage (high lactic-acid presence).
• Unfortunately, domesticated living usually challenges the horse's sensitive digestive tract with inappropriate ultra-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.
• Avoid any sweet feeds (Musli's/Beet) and/or sweetened haylages advertised with cherry or apple flavours - you're simply feeding the acidic inflammatory gut bacteria which causes them to multiply and kill off the beneficial microbes that do all the good stuff like digestion and fibre fermentation.
• Keep your horse moving – movement equals gut motility. 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 - all the better if it's long grass. Not only is the horse free to consume the ideal fibre diet, but the simple, continual act of moving to eat, enhances motility of keeping the food moving along in the gut.

And there we have it - gut page done. Meanwhile, click on the SHOP link below to see our complete Gut System product range, and the other chapters in this section.

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