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, and trust me - size matters
5. Digestion - it's all about the how
6. A quick intro to the all-important Microbiome, the body's 2nd Brain
7. The Hindgut Acidosis/Dysbiosis/SIBO/Leaky Gut/Autoimmune domino effect
8. The critical Gut:Liver:Kidney & B6 (P5P) connection
9. Could it be KPU?
10. Faecal water/diarrhoea
11. Ulcers
12. Colic
13. 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 right and making sure things are moving smoothly. For starters, more than 70% of the immune system is produced and housed in the gut. And there’s more to those “gut feelings” than we think - the gut and brain are actually connected - the brain can impact the quality of the digestive tract lining and the release of chemicals to support healthy digestive function. And 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 actually produced in the gut.

Whether human or horse, caring for the digestive system as a whole should be a priority, as the overall health of the gut is going to influence behaviour, 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 for those regular followers here, my favourite subject - diet, which 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.

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. Everything starts with the gut, but ... everything begins with the gut microbiome, and it all depends on the healthy integrity of those friendly fibre-fermenting microbe colonies in the hindgut, who produce all the vital metabolites which fuel both the horse's energy and the body to thrive.

The horse's hindgut region/colon is the deciding point as to whether we have a healthy horse or not. Those friendly hindgut microbes, as in the microbiome that reside in the colon, normally live perfectly happily, fermenting all the lovely fibre from the grass forage that the horse has eaten. However, if that delicate balance between friendly v. unfriendly microbes becomes disrupted, i.e. triggering a rapid overpopulation and colonisation of the unfriendly acid-forming microorganisms, this forces a drop in the pH level, creating an acidic environment known 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. What happens is that some of those unfriendly acidic bugs from the hindgut will have moved up into the small intestine, which isn't good 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 bad bacteria move in and take over, they'll start fermenting the digesta in the small intestine, i.e. the sugars, starches and proteins. In humans this is what causes IBS.

Worse still, this can lead to leaky gut, where the gaseous inflammation in the small intestine, triggered by those unfriendly, acidic bacteria, becomes so pressurised (think of a balloon being pumped up) that it can tear apart the very fragile intestinal wall.

(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 accounts for around 70-80% of the body's total immune system. So, if we've got a leaky gut, we're now in real trouble because pro-inflammatory bacteria, along with particles of putrefactive undigested matter from the small intestine, will now leak into the bloodstream and wreak toxic havoc in the body, activating an emergency immune response and driving the immune system into a manic, panicked overdrive.

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, and a healthy microbiome the game-changer - this may very well be the decade, or even the century, of the microbiome.

The gut microbiome is probably the most important regulator of health; there are over 100-trillion gut microbes sending messages throughout the body, interacting with the hormones, the immune system, brain chemistry, and every other system in the body. When the microbiome's microbes are are out of balance, a malfunctioning body is the result. It really is as simple as that.

But why does this happen? 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 horse's digestive tract still looks exactly the same and works exactly the same as their ancestors' gut systems did. The most common reason, however, is that we've taken our eyes off how and what we should be feeding them and what should be passing through the intestinal tract. For the last half-century or so, we've believed the spin fed to us by emerging animal feed producers and instead of feeding our horses with species-appropriate nutrition from grass forage fibre, we've fed them pro-inflammatory, gut-damaging junk food.

We need to go back to relearning 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 start at the beginning, with 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 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. The good news is that a horse knows exactly how to do it so we need to start taking our lead from them all over again 😏.

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 they've bitten off into tiny pieces of between 2-5mm - yes that's millimetres. This length is vitally important as the whole digestive process, including peristalsis motility, takes place through a very long - and thin - tube, the intestines to be exact, from start to finish, and successful digestion is entirely governed by the chewed and ground-down length of the fibres.

This means there could be a potential problem with most chaffs because they're generally made of grass fibre lengths between 1 and 5cm - that's centimetres - which horses can't thoroughly chew as they're too short, but they're too long to be properly digested. The horse then swallows these too-long fibres, which then alters peristalsis motibility, which can cause the fibres to remain festering in the colon for up to a week. This promotes gut dysfunction which can then lead to a gut-disruptive cascade and various metabolic disorders. An obvious sign is if your horse's droppings are a bit stinky, or smell 'rotten'.

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 organic, diverse multi-grass species requirements, but there's also a very simple solution to this - don't feed a chaff. Seriously. They don'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 tiny pieces. Job done.

Edited to add (Sept'22) - I've since found the Agrobs' Senior Chaff is cut near as damnit to the short requirement, and because my 28yo connie, Murf, lost a tooth this year with his others described as 'worn', he's going to stay on this forever now.

Back to chaff and ideally, the optimal chaff fibre length is around 8cm 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 ensured adlib hay, with plenty of fibre going through the hindgut, features as the main grass forage.

*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. Make sure they're 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.

In a natural environment of free-growing long, stemmy grasses (er, not what we generally have here in the UK), the horse will bite the right size mouthful size 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 means the job's done, ready for the huge process of digestion. 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, it's a done deal.

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 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 – apparently the forage length needs to be 8cm 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 good to be mindful of the fibre length.

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

3. Digestion - it's all about the how

The chewed food bolus 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 before it's 'disinfected' by the stomach acid and turned into a soupy mix called chyme, so it can pass easily into the small intestine (SI). 

Now the microbiome's microbes start to separate out the essential nutrients - proteins, starches, carbs, fats, plus micronutrients (vitamins, minerals) - 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 fibre-fermenting microbes set to work on the fibre and produce vital metabolites (postbiotics) such as vitamins, 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 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, keeping the friendly commensal 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 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 to 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 - this is so important as so many equine health issues are caused through not having enough forage when stabled and letting the stomach become 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 gut needs a neutral pH - it's a huge problem if any part of the rest of the digestive system becomes acidic (which sadly is very common these days).

The stomach acid is there for a massively important reason, well, two actually. Firstly to kill off contamination that's come in on the forage. Stomach acidity is the bodies’ first defence against harmful bacteria, but just as an aside, 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 pathogens straight through a wide open door into the intestines, damaging the microbiome.

Without the acid we risk contaminants entering the small intestine, and worse, impaired protein digestion. And when undigested protein gets 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 “does change the microbiome for the worse”, and increases the risk of gastrointestinal infections.  Stopping taking Omeprazole can be even worse 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.

Secondly, the stomach acid activates the protein digestive enzyme, pepsinase, into pepsin, without which, 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, so not too acidic - 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 they actually have a useful job to do.
  
  These 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, the 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. (PS - this is also the region where the horse experiences squamous ulcers, caused by inappropriate feed or when the stomach has been starved, i.e. not enough hay in the stable, and therefore allowed to empty).
  
  PPS - don't be confused by thinking LA bacteria are friendly as they're really not - if they manage to slip through into the intestines, we're in real trouble - see our separate page on Hindgut Acidosis (link also below).

• Now to the middle section, and this is where the pepsinase enzyme, the protein digester, is produced. This then needs to be activated into pepsin by the stomach acid to perform the protein pre-digesting. 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.

• The back section, pars glandularis, is where the hydrochloric acid sits - its role is basically to disinfects any nasties in the feed such as microbial contamination (it's how dogs survive eating other dogs' poop, as well as other revolting rotting foodstuffs, with their acid pH value at a super-severe 1!). This is also where, as mentioned earlier, the protein digestive enzyme, pepsinase, is activated into pepsin, and can now start to degrade the proteins in the feed. Horses 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, but not 100%. (PS - this is also the region where the horse experiences glandular, aka pyloric ulcers, caused by stress resulting in poor blood flow to produce the protective mucus layer on the mucosa membrane).

In summary, here's the normal foregut process :

• a horse should have a constant uptake of roughage so that the stomach remains constantly full, active and operating.
• a pre-digestion of starch via LA bacteria in the first section producing LA.
• pepsinase production in the middle section.
• the back section activating 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 all the 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 to digest the fats, while the small intestine's microbes assimilate the nutrients ready for absorption. 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. And all the while there have been fluids and mucus to lubricate and keep everything moving along the way as well.

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. If digestion is impaired, so will begin a cascade of seriously chronic dis-ease (meaning the body is ill at ease).

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 inner gut-environment and preventing SIBO - which as we said earlier can lead to leaky gut syndrome if left untreated, which for the record is now so widespread amongst our equines 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.

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 - feed a constant supply of quality, high-fibre, grass forage (hay)and roughage - barks, woods and roots - to add valuable, natural, prebiotic diversity feed for the hindgut microbes to chow down on - see our WildFed. 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. 😉

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 (coprophagia) are thought to be obtaining 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 gotten a bad reputation. But these bugs in our gut microbiome actually do a huge job - they help digest food and sort out the nutrients for absorption; 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, becuase

gut health IS health.

Collectively the beneficial friendly and unfriendly microbes outnumber the regular cells in the whole, entire body, by an astonishing 10-1 at least (!). Think about that for a second - that's a whopping 10-times more bugs in the gut intestinal tract, that long tube from mouth to the final exit point, than in the whole of the rest of the physical body. 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. Over 70% of our horse's immune cells are created by the gut microbes in the intestinal tract and 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.

Unfortunately, there are certain medical protocols which can really mess with the gut ecology, such as antibiotics, bute, PPIs 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 completely wipe out the gut bacteria, the bad bugs as well as the good bugs the body can’t live without. Feeding activated charcoal will also have this effect as well because it doesn't discriminate between good and bad bacteria, which is why it's great if you're having your stomach pumped in A&E, but not so great if you're trying to shift some bad bacteria 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.

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 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/Autoimmune 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

Time and time again, our clients' horses struggle with autoimmunity issues when their horses' gut systems have gone haywire, but issues within the gut aren’t just limited to autoimmunity. The 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. This means when issues linger in the gut for a prolonged period of time, they show up in various forms throughout the rest of the body too, and it all starts with dysbiosis in the gut microbiome.

Microbiome dysbiosis is when that very fragile microbe balance within the gut microbiome environment is disrupted and the biome/microbe ratios are not what they're supposed to be anymore, i.e. more of the unfriendlies than the friendlies. Cue a fault in the vital fibre fermentation process.

The lining of the gut's small intestine 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, in order to avoid dysbiosis. Another fact - it's the microbiome, as in a healthy one, filled with lots of happy, beneficial microbes busying away down there in the hindgut and fermenting the fibre in the hindgut to produce the vital metabolites that help the horse function, that regulates the permeability, aka leakiness, of the gut wall lining - this is the connecting factor.

When the gut bacteria balance is disrupted and the bad bugs outnumber the good bugs, those bad bugs set up camp and create inflammation. For starters, the inflammation 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 triggers an almighty inflammatory autoimmune cascade as the immune system goes into hyper-overdrive, trying to fight those leaked toxins.

Cue the battlefield. 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.

Vaccines don't help either, as vaccines can 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, to grow the antigen. 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.

More on leaky gut in our Blog Leaky Gut - a new epidemic?

6. 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 liver/kidney function, specifically a dysfunction in the detoxification process, because when there’s leaky gut, there’s an overload of toxins for the liver to 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, but if there’s a toxicity overload the kidneys become overwhelmed as well, so can’t shift all the toxins quickly enough out through the urine. Result? These toxins get flushed back round 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, which can explain why there’s sudden ‘skin’ tenderness or inflammation, or unexplained tendon/ligament/muscle issues.

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. Here’s why.

The hindgut produces B6 in its activated form – this is really important - being produced in its activated form. Scientific name Pyridoxal-5-Phosphate, aka P5P, and absolutely not the synthetic form we see in off-the-shelf B-vit supplements (Pyridoxine), which the equine body neither recognises nor knows what to do with, so shunts it straight out for excretion. (As the saying goes, 'An expensive way to make urine' 😉. Seriously, save your money, as well as the extra work on your horse's liver and kidneys).

I digress. However, 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 form - P5P – to break down/metabolise/biotransform – those toxins. So, if the liver and kidneys can’t do their job, the whole natural detoxification process gets messed up. This is all very much connected to a now widespread multi-metabolic detoxification disorder called Cryptopyrroluria, aka KPU, which since the science on KPU came out around 2021, it really is the key to so many metabolic disorders that owners have previously struggled with, unable to get to the bottom of them. And all because P5P wasn't being produced by the hindgut microbes.

Worse, not only is there the toxicity overload, but these toxins are also damaged, dangerous, putrefactive (relating to or causing decay) toxins because the liver hasn’t been able to break them down properly, and this is why the presenting symptoms can be such a profound 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 gut:P5P:liver:kidneys restoration programme is needed, all covered on our KPU page. The good news? We sell P5P, and since 2021 it's proved to be a godsend to horse owners, including me with our MacAttack pony, alongside a thorough gut restore and feed tweaks where necessary.

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 nurture the biota to make it flourish, so it can produce all those vital nutrients, aka postbiotics (which include producing the B-vits and several amino acids) that the body needs to be healthy. See our Blog Prebiotic Foods for Postbiotic Abundance for more on this story.

Meanwhile, what if it is KPU?

7. Could it be KPU?

So, we know that many essential nutrients are produced by the hindgut biome, known as postbiotics - these include several amino acids, vit.K, vit.B12, and the 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 we have to regenerate the hindgut microbiome, 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 too leafy with no stemmy fibre, and 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, back into the hindgut to rebalance the biome.

If haylage has been fed, the gut also needs to deacidify, so feed Spirulina for a couple of weeks. 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, with 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 basic the feeding program – 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 every-thing 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. 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 cast-iron guarantee that they'll upset the intestinal flora, never mind the liver. Only worm if you know your horse has a known worm infestation and not as a precautionary measure.

• Avoid empty feed periods of more than four hours as this leads to a breakdown of the intestinal flora. Ensure adlib hay 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 and not so friendly for the ones we don't want in there.

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

• Spirulina helps stabilise the pH level while effectively relieving excess toxins. Again feed 20g/day for 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 ...

8. 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 meltdown, due to poor feed practices and/or ongoing chronic stress. I know that no-one plans to feed their horses inappropriately, but there's so much spin and misinformation out there that it's too easy these days to get it wrong. That's why we're here to untangle the BS, so let's deconstruct this dreadful syndrome to understand it better.

During normal digestion, the resulting waste is formed into faeces, becoming thicker and forming into the round-ball shapes that we’re 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. Didn't take long for me to change that habit!). Faecal water can also occur in specific situations – for example, if the horse is under stress.

What actually happens

The large intestine depends on a very precise pH value; in a healthy horse, this value is between 6.8 and 7.2 (neutral range). A lower, acidic pH value causes inflammation of the intestinal mucosa If the intestine becomes acidified, as in the pH value drops below 6.8 and this kills off the essential friendly microorganisms.

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 ‘tears’, aka leaky gut syndrome. This causes the faecal water to become self-perpetuating, as the absorbed fluid is able to flow back through the tears 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. The faeces and faecal water are usually very acidic, which, in turn, causes further inflammation of the intestinal mucosa and creates additional tears. 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?

Particularly acidic feed (i.e. haylage) and lactic-acid bacteria in the digestive system (from haylage, but also horses fed with lactobacillus and ‘bifido’ cultures) have an effect on the horse’s intestine. As we repeatedly mention on this website, lactic-acid bacteria are absolutely not part of the horse’s natural intestinal flora; the bacteria prefer pH levels below 6, which is way too low for the horse’s intestinal environment.

Lactic acid bacteria break down the proteins and sugars found in roughage, but not the structural carbohydrates. They do not make molecules which the horse can use for energy production; instead, they form lactic-acid molecules which acidify the intestines, which in turns strengthens and multiplies the lactic-acid bacteria. The beneficial gut microbes can't live in an acidic environment, so they're killed off. Cue significant dysbiosis.

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 any 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)

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 produced in the hindgut by lactic-acid bacteria.

FACT - Squamous gastric ulcers occur when acids produced in the stomach, i.e. hydrochloric acid, come into contact with the wall of the upper stomach (called the squamous region). This region does not have a protective mucus layer, like that found in the lower, glandular region, where acids are secreted. (Glandular/pyloric ulcers are caused by stress resulting in a poorer blood supply - see our Ulcers page for the full story).

Which means – 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, and the stomach acid will then splash onto the exposed stomach wall and create an ulcerated sore, because hydrochloric acid is almightily strong acid, same as a car battery. 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 - 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 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 needs into your care, 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 a 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 all about a pretty 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 - 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 crazy to even think about rationing it.
• Additionally, the more horses chew, the more 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.
• Definitely don't feed haylage (high lactic-acid %).
• 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) - 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.
• Keep your horse moving – movement = 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. 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.

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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