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The Liver

Updated Oct'21

The equine liver is considered the body’s central chemistry lab - wherever metabolism takes place, the liver is involved.

It’s also huge – hold your arms up above your head and bring your hands together – that’s the size of the liver.

Support the liver and the liver will support the body right back - clear skin, good energy, strong digestion, and a healthy immune system. Ignore it, and you’re looking at compromised detox function, poor skin, sluggishness, trouble digesting fats, seasonal disturbances, irritability, inflammation … as well as allergic responses due to a buildup of metabolic wastes.

When it comes to holistic liver care, it’s not just about the right food. A supportive lifestyle is also one of the number one tools for achieving optimal liver health because stress hormones also compete with the liver’s filtration system. Remember that the liver is the body’s master filter - in addition to deactivating harmful substances that come in, the liver also filters and deactivates the body’s own chemicals, such as estrogen, histamine, and stress hormones such as cortisol.

And just as an aside, and to quote Charlotte Gerson, founder of the Gerson Institute, "All drugs (conventional pharmaceuticals) are liver toxic, bar none."

The liver is also an absolute part of the digestive process – it’s as important for the digestion process as the gut because all the nutrients digested in the small intestine – sugar, starch, fat and protein – first go to the liver, and the liver has to process them before they go to the rest of the body. In our modern world this is a huge amount of work that the horse’s body has to do because back in the day, the wild horse’s liver never had to deal with such high nutrient values in their feed.

At the same time the liver also has to deal with all the byproducts from hindgut dysbiosis, so when the wrong microbes start multiplying, they produce a lot of toxic waste from their own metabolism that the horse can’t use, which means the liver has to process them as well so they too can be excreted.

Quick digress – unlike the human or dog gut system, the horse is different. The equine small intestine isn’t the main digester – the hindgut, the large intestine, is the main digester, breaking down fibre from grass forage and roughage by the hindgut’s microbial fermentation processes, and this process is vital as it creates the horse’s main energy source via three volatile fatty acids - Propionate, Butyrate and Acetate. These can then readily – and directly – be absorbed by the body’s cells straight from the hindgut - they don’t have to be metabolised by the liver - and can be directly converted to ATP energy by the body’s cells. See our ‘Fix the cell to get well’ page for the full ATP story.

The liver’s multi-talents

Detoxification function for metabolic waste and toxins Probably the most vital of the liver’s tasks, but as mentioned above, the liver doesn’t do the actual detoxing – it biotransforms the toxins into a form for the kidneys to be able to excrete them; detoxification is very much a synchronized liver/kidneys process working together to detoxify the body.

Bile secretion The liver produces bile and bile salts, critical for digesting fat and for the absorption of fat-soluble vitamins. Bile is necessary to activate digestive enzymes in the small intestine to start peristalsis. It also creates an unfriendly environment for microbes in the small intestine, so no fermentation processes occur here – fermentation (should) only take place in the hindgut/large intestine. For the bile-eco-nerds out there, bile is also an awesome self-recycler – at the end of its role in the small intestine it’s then absorbed back into the bloodstream, to be returned to the liver and remade into fresh bile again 😉

Carbohydrate metabolism and blood sugar regulation The liver helps regulate blood sugar by converting excess glucose into glycogen - an energy form that can be saved for later use. When a horse consumes sugar it arrives in the small intestine, is absorbed through the intestinal wall and transported into the bloodstream. Blood sugar levels then rise – if it’s in normal amounts the horse is fine, but if it’s too high? The pancreas monitors the blood sugar level and as soon as it goes up it releases more insulin hormone, which binds to the liver cells with a warning - “Hey, there’s too much sugar in the blood so reduce it now.”

So, the liver takes up the sugar from the bloodstream and the blood sugar lowers. It’s not gone away though – it’s gone into the liver cells which have storage cells for sugar, but in high amounts this is toxic, so the liver cells start to change the glucose to glycogen – a storage form of glucose. The glycogen stores can become full as well, so you can see how hard the liver is having to continually work while the pancreas keeps releasing insulin.

Fat metabolism This is when fat is created from the glucose molecules and the fat is then stored in the fat tissue. This works for most animals but it’s not great for horses as they’re constant feeders, unlike most other animals. In evolution most predator breeds need to create fat because they generally have long periods of non-feeding, i.e. a wolf kills a deer, and their body will store excess energy from it in the form of fat for the next 2/3 days, in case no more prey is caught. All predator animals can store fat and re-use it as energy.

Horses don’t – can’t - because evolution created them as constant feeders, continually moving to new landscapes to find forage/roughage feed, so storing fat as energy is an unnatural state for a horse. It’s not only unnatural – and extremely difficult – for a horse to build fat, but also to reuse the fat as an energy source, so basically, excess sugar creates a toxic state for the horse.

The horse’s system compensates for it by changing the conformation of the sugar to glycosaminoglycans which are stored in the connective tissue. A horse can store a lot of water-soluble toxins in the connective tissue until the kidneys are able to excrete it. As an aside, we have 2 types of horses – those that get fat from sugar excess, and those who get lymphatic from sugar excess as they’re not able to build fat, even tho it looks like they’re fat, so we have to determine if it’s lymph or fat, but that’s a whole story in a whole other chapter to come … 😉

Protein metabolism Protein is taken apart in the small intestine and broken down by the protein digestive enzymes into amino acids, which are absorbed through the gut membrane into the bloodstream. The liver converts these to albumins – storage proteins for the body, and the body’s cells take up the albumin and use it as a source for their own protein metabolism. However, if there’s too much protein in the diet, the liver creates urea and uric acid which the kidneys then process for excretion.

Meanwhile, when a horse needs energy with not enough coming from its forage fibre, i.e. they’re in heavy training so their energy consumption goes up but feeding volume remains level, you’d think a horse would lose weight, but - they don’t. They’re able to get more energy by better optimising the digestibility of plant fibres. If they do need more energy, the next source is proteins – they start digesting muscle proteins, i.e. muscles not needed for training requirements are degraded. When this is all used up and still extra energy is needed, only then comes the point where the body uses fat as an energy source.

Enter the ketone pathway – you may have heard of the Keto diet in humans (which for the record I personally follow – most of the time). Thing is, the pathway to create energy from fat is not well established in horses – it’s great for humans/dogs but not horses, because in horses it triggers a dangerous condition called hyperlipidemia, which means abnormally elevated levels of lipids (fats) or lipoproteins in the blood.

An example – some owners think that feeding straw to their will help them lose weight, so they stop feeding hay. A major Wrong. Straw is a wood fibre (lignan) and can’t be digested in the hindgut, so a horse can’t get any energy from straw, hence it literally starves with a full stomach but no energy source. If a horse is fed only straw their body will have to use stored energy resources, i.e. protein and fat, which leads to hyperlipidemia. The bad new is that horses will die from this because horses simply can’t generate energy from fat.

The liver is responsible for all the metabolism of excess sugar to be remodelled and stored by the liver, and when the body needs more energy the liver is mildly involved in the creation of this from fat or protein. The master energy source for a horse is from plant fibres in the form of propionate, butyrate and acetate volatile fatty acids by the hindgut microbes and not in the form of fat or protein, so fat/protein needs to be taken out of the energy calculations when feeding our horses. The horse’s metabolism only uses fat/proteins to build body parts and for cellular regeneration, but not as an energy course – fibre, and only fibre, should be considered as the energy source, otherwise the liver has a really tough time dealing with it all.

Long and short, be aware that every time we feed our horse we may be overloading the liver with too many unnecessary nutrients the body doesn’t need, which restricts its capacity to do its main job, i.e. the detoxification of waste products.

Hormone balance This is really complex in horses and for good reason; hormones can be likened to an orchestra which has to work together to create a symphony, and when one instrument doesn’t work well, the symphony collapses. When we see hormonal problems in horses, i.e. a gelding still acting like a stallion, it’s not that the vet forgot something during the surgery, because it’s not only the sex glands producing the hormones, it’s also the adrenal glands. Every gelding will still have testosterone and every mare has testosterone, just as both mare and gelding also have oestrogen. So, if you have a gelding acting like a stallion, look first to the adrenal glands but also at the liver, because … Most hormones are degraded by the liver, including the sex hormones and cortisol. It could be that too much hormone is being produced but not enough of it is being degraded, so before messing with the glands, tone the liver first.

Participation in water balance regulation When it comes to water retention i.e. lymph pads, puffy legs, a thick lymphatic neck or cellulitis/phlegmon, always look at the liver and kidneys – both organ systems are part of the water regulation system in the body.

Vitamin and nutrient storage In addition to storing glycogen, the liver stores fat-soluble vitamins A, D, E and K, and trace elements, i.e. copper/zinc, so if we don’t feed a mineral balancer every day, the body takes them from the liver stores and uses them. They then need to be refilled.

Blood storage, as well as blood formation pre-birth The liver holds 25% if its own weight in blood volume if needed, so if a horse loses a huge amount of blood loss, say due to an accident/surgery, the liver can donate 25% of its own weight in blood.

Just as usefully, blood also gets drawn from the liver during times of fight/flight – the blood gets shifted from the inner organs to the muscles so the horse can run away fast from any perceived threat. The body doesn’t have enough blood volume to have enough blood for all the organs all the time – it always has to shift to where it’s needed, i.e. when the horse is suddenly put in a fight/flight or sudden stress state, so when the horse isn’t under stress, i.e. chilling, eating, playing with their buddies, most of the blood volume is in the inner organs, and especially the gut system and kidneys – all the organs involved with digestion are very well supplied with blood.

The muscles are averagely supplied with blood because horses don’t gallop while they’re feeding – slow walking also doesn’t involve a lot of walk for the muscles.

How stress affects liver function

A word of note – the living conditions that some horses are kept in these days often means a constant state of stress. Typical examples:

  • being permanently stabled (racing/competition yards)
  • a horse very low in the hierarchy
  • multiple herd changes - a horse needs at least 3-6 months to settle in a herd so a changing herd is constant stress for horses
  • not enough feed – there are still so many examples where owners simply don’t understand the importance of adlib forage being left in the stable overnight, and don’t understand how seriously detrimental it is for a horse to run out of forage
  • nowhere to sleep
  • inability to move in a stable – horses need to walk around freely
  • an aggressive stabled neighbour

Horses can often live under constant stress which means the liver is usually only running at 75% of its capacity because 25% blood volume is already being pumped to the muscles. And when you consider how many tasks the liver already has to do, when you combine this reduced capacity, then with its added jobs – hindgut dysbiosis, mouldy hay, high toxin load – all the systems get out of balance.

We can see liver parameters in bloods – if a horse eats a toxic plant the parameters will rise, but 2-wks later they’ll be down again, but if you take them regularly and they’re constantly elevated, then we need to rethink how we’re managing our horse’s lifestyle, and the very real possibility that there’s a liver problem.

Early markers

There are early markers for poor liver function before showing in the blood :

  • Single white hairs in the coat. This is normal with aging – they spread over the face/neck then the body, but in younger horses it’s not normal. Black horses show reddish-brown, bay horses reddish tips in tail/mane.
  • What’s known as famine hairs – single long hairs in the coat, only in winter, and they’re the last to shed as well.
  • Vertical stripes in the coat on the thorax and abdomen, about 2cm apart – the colour’s no different but the hair is slightly off centre so the light shines on it differently.
  • Dark spots, especially in chestnuts and/or palominos in the flank/croup, like oversized freckles.
  • Super-sensitive skin – regularly overly itchy, big bumps from insect bites, rug-sensitive, and if extra care needs to be taken with pharmaceuticals/poor quality feed.
  • Fetlock tendosynovitis – tendons are made from connective tissue which, remember, is one of the pathways for toxin storage. We tickle on as normal with everything seeming fine for ages, then mysterious swelling can start just above the fetlock, more or less symmetrically on both hinds. It doesn’t go away despite exercise, then can appear on the fronts as well. Regeneration of the tendon tissue is reduced and leads to inflammation, so there’s less tendon fibre and as a result it appears thinner; now we’re talking too much pressure on the tendon, eventually leading to tendon rupture. And while we’re on the subject of tendons … non-accidental tendon issues as well.
  • Blue shimmer on the eyes, frequent eye infections, constantly lacrimosal.
  • Puffy lymphatic legs which improve with movement.
  • Loss of performance, poor muscle buildup.
  • Sensitive, lifted abdomen.
  • Light colicing, change in faecal consistency.
  • Overly hot! As a byproduct of strong metabolic activity, heat is generated which makes up a significant part of the body’s core heat.

Supporting liver health - bitter is better

Bitter foods are especially supportive for the liver. Ayurvedic medicine considers the liver a pitta organ (fire and water), so foods and herbs with a cool energy and bitter taste help reduce and pacify pitta energy (dosha). Western herbalists also agree that bitter foods and herbs are beneficial for the liver, so fill that feedbowl up with fresh dandelion leaves, one of the best bitters out there!

Garlic is also really useful for liver detoxification as it helps where wastes are mixed up into water-soluble byproducts that can be excreted via urine and faeces.

Meanwhile, herbs are the icing on the cake when it comes to holistic liver care. While a supportive lifestyle and diet are the foundation of liver care, herbs give that extra boost of support in maintaining and regaining liver balance, the most prominent being:

  • Burdock (Arctium lappa) root - a liver mover, meaning it helps ease a sluggish liver by encouraging bile excretion and production. It also contains inulin, a prebiotic fibre which nourishes the friendly gut biome.
  • Milk Thistle (Silybum marianum) - probably the most well-respected liver protectors, milk thistle defends the liver against even the most extreme toxins.
  • Dandelion (Taraxacum officinale) root – a nutritive liver mover. The leaves are generally used for kidney support and have a diuretic action, whereas the root is a wonderful liver supporter.
  • Aloe (Aloe vera) juice - both cleansing and rejuvenating and has a special affinity for the liver, being one of the best cooling options for balancing pitta dosha. It’s both purifying and revitalising for the blood and is indicated when there is evidence of waste build up in the blood, liver, and GI tract. Found in all good healthfood shops.