Dehydration is a condition in the horse where there is an inadequate amount of fluid in the body and/or unbalanced or insufficient levels of electrolytes in the fluid. Clinical dehydration occurs when a horse has lost 5% of its body fluid through excessive sweating, acute diarrhoea, electrolyte losses or inadequate intake of drinking water. A deficit of 1% in body fluids can reduce performance.

Water is a critical nutrient for life and is needed by the body for normal functioning. The water content of a horse is between 68-72% of body weight on a fat free basis. A spelling horse in a mild climate requires 5 litres of water per 100kg bodyweight per day. An adequate intake of clean water is needed for normal digestion and absorption of digested feed and in maintaining normal blood volume in the body. Water is also vital for the normal function of sweat glands and maintaining normal body temperature. Horses should always have access to clean, fresh water at all times so they can self adjust their intake according to need. Water is lost from the body in faeces, urine, sweat, exhaled breath and milk in the lactating mare.

Electrolytes are sodium, potassium and chloride ions that circulate in the blood to all the tissues of the body and are vital for normal cellular function. They are required as macro minerals and are required on a daily basis in the diet as they are not stored in the body.

Heat related dehydration

The main way a horse loses excessive body heat is through sweating. Horses have a high muscle to body weight ratio and a low skin surface area to body ratio compared to people. This means they build up heat more quickly during exercise or in hot weather and take longer to lose heat and cool themselves. Horse sweat also contains significant amounts of electrolytes, they can lose up to twenty litres of fluid in one hour of sweating.

Water intake dehydration

Cold weather can interfere with a horses thirst mechanism and can result in dehydration due to insufficient intake.

A high water intake with the absence of sufficient electrolytes will dilute the electrolytes still circulating and result in the kidneys excreting more water and taking more electrolytes with the water. Unless adequate amounts of electrolytes are supplied through food or water the horse will become severely ill or even die from the imbalance in its body of water and electrolytes.

Mild dehydration will result in reduced performance, weight loss, reduced feed consumption, colic and constipation. more severe dehydration can cause thumps, exhausted horse syndrome and tying up. While a skin pinch test will give a rough guide to a horse’s status regarding dehydration, a blood test will give an accurate result of how dehydrated a horse is. Treatment is aimed at restoring normal fluid and electrolyte levels and should be done under veterinary supervision. A management protocol should then be put in place to prevent it occurring again.

Dehydration is not limited to hot weather and for horses in hard work, daily electrolyte supplementation is the best preventative measure and is recommended for all horses and ponies at all times. Equilibrium and Lexvet supplements are ideal for all equines and contain the macro and trace minerals required by horses as well as vitamins and electrolytes for good health and performance. The dose per day varies according to size, workload and whether a mare is pregnant or lactating.

Dr Jenene Redding BVSc (Hons)

Anhydrosis – Drycoat Syndrome & Puffs – Non Sweating Disorder

What is anhydrosis?

Anhydrosis is the partial or complete inability to sweat in response to high body temperature. It can also spontaneously reverse.

Some background:

The skin is the major organ of the body and it has a multitude of tasks. One of these tasks is to regulate the horse’s body temperature. This is achieved by the skin through sweating when the horse’s body temperature is too high. The sweat glands are densely packed in the skin – averaging 800 glands/cm2. They are a tubular coiled gland that exits the skin at the hair follicle. They have a rich blood supply and are surrounded by nervous tissue. They appear to be stimulated by both the nervous system and hormones in the blood stream.

Horses are unique in that their sweat (and saliva) contain latherin – a soap like protein that reduces surface tension and spreads sweat easily over the coat. The cooling effect comes from the evaporation of sweat. it is the latherin that causes the white foam seen on some horse’s coats when sweating. Horses can lose up to twenty litres of sweat per hour and can lose 4 -30 kg of body weight when exercising. Electrolytes are secreted in the sweat and consist of sodium, potassium, magnesium, calcium, chlorides, sulphates, phosphates and bicarbonates. They lose three times more sodium than people and ten times more potassium.

When a horse exercises it produces heat in the muscles which is absorbed by the blood stream. As the blood circulates through the lungs some of the heat is lost as the horse exhales. As the blood circulates in the skin it loses heat by radiating it out. If the core temperature continues to rise the hypothalamus in the brain sends hormones to the sweat glands to tell them to produce sweat.

What causes horses to overheat?

• Hot and humid weather is a major stressor for horses as the humidity effectively prevents evaporation of sweat.

• Overworked unfit horses will sweat profusely.

• Nervous and agitated horses will also sweat profusely as their core temperature increases.

• Dehydrated horses can overheat because they cannot sweat adequately to lower body temperature.

• Inappropriate rugging of horses in hot weather

• Horses unable to access shade and cool water will also overheat.


What causes anhydrosis?

It can occur in any breed at any age and can occur overnight. The exact cause is unknown but chronic or acute lack of electrolytes can trigger anhydrosis. The sodium and potassium losses associated with sweating actually cause a decrease in thirst and appetite which leads to further dehydration.

It is also thought that constant and continuous stimulation of sweat glands, especially in very hot weather, may cause them to shut down.

What are the signs of anhydrosis?

There is very little, patchy or no sweat present after work or on hot humid days. They have a higher than normal body temperature and an elevated pulse. recovery is slow after exercise and they may appear distressed. puffing is a response of the body in trying to compensate for the lack of sweating. Their coat may appear flaky and dandruffy if they have had the condition for some time.

How to manage anhydrotic horses.

• Hose with cool water before and after exercise.

• Keep hosing and scraping water until the respiratory rate returns to normal.

• Only exercise in the cool of the morning or late evening.

• Keep susceptible horses in stables with fans, cool water mists and regular sponging down.

• Very cool drinking water will help lower core temperature faster than warm water.

• Allow paddocked horses access to dams or creeks to stand in.

• Only rug if absolutely necessary and use white 100% cotton rugs.

• If a particular horse is absolutely non-adaptive to a hot humid environment then it would be in the horse’s best interests to relocate to a more temperate climate.

• Supplement with a complete mineral and vitamin product such as Equilibrium or LexveT to supply all the minerals needed for sweating.

Dr. Jenene Redding BVSc (Hons)

Anaemia and Nutrition

What is anaemia?

Anaemia is a deficiency in the number or quality of erythrocytes (red blood cells) that are circulating in the blood and that are stored in the body.

There are several types of anaemia, each with different causes and treatments. as treatments vary depending on the type of anaemia, it is important for the vet to advise you on the type of anaemia your horse is suffering. These include:

1. Blood loss anaemia

Ulcers, parasites, trauma, haemophilia.

2. Haemolytic anaemia

Infectious, toxic causes autoimmune, eg isoimmunisation of foals

3. Dyshaemopoietic anaemia

Selective depression of red cell production due to poor nutrition (deficiencies of iron, copper, cobalt, protein and B vitamins), parasites, viruses, bacterial toxins. in the case of horses having viral infections there is often bone marrow suppression and a subsequent anaemia and lymphopaenia (reduction in white cells) occurs. These are generally self limiting and with recovery the cell counts return to normal. extra iron supplementation is of no value in these kinds of anaemia.

4. Aplastic anaemia

Red and white cells are depressed as are platelets- typically caused by radiation poisoning, toxins (eg. pesticides, arsenic)

Anaemia can also be described by its appearance – cell size changes are described as normocytic, macrocytic and microcytic.

The haemoglobin content is described as normochromic or hypochromic. These descriptions can help to determine the cause of the anaemia.

What is the function of erythrocytes?

They are needed to transport oxygen from the lungs to all the cells and tissues of the body. Oxygen is the fuel that enables cells to function in order to maintain life. The life span of an erythrocyte is approximately 145 days in the horse. The cells are broken down in the liver, spleen and bone marrow. The proteins are conjugated in the liver and excreted in bile. The iron is stored in the liver and then transported to the bone marrow for the manufacture of new red blood cells.

How does a laboratory measure erythrocyte numbers?

The packed cell volume (pcv) is a percentage measure of the mass of erythrocytes in the fluid component of blood. A normal pcv is in the range of 32 – 53%. The spleen is a reservoir of erythrocytes should extra ones be needed in the circulation for exercise, trauma, shock and excitement. The pcv can be falsely elevated by splenic contraction and dehydration. a laboratory can also look at red cells in blood smears to check for their size, shape and colour. This then determines the type of anaemia that is present.

What causes anaemia?

Anaemia can be caused by blood loss, chronic inflammation and viruses. increased destruction of erythrocytes can occur with auto immune diseases and toxic chemicals. Reduced production of erythrocytes can occur with major nutritional deficiencies and cancer of the bone morrow. It is important to remember that anaemia is a symptom of an underlying primary problem that needs to be correctly diagnosed in order to ascertain the cause.

Dr. Jenene Redding BVSc (Hons)

A discussion about iron metabolism in horses

The following discussion is a summary of what is known about the metabolism of iron. Some of this material is drawn from human research and is extrapolated to other species. All animal species that utilise oxygen as fuel for energy have incorporated the use of iron. Across all different species of organisms, the principles remain largely the same.

That said, research still needs to be done to further clarify how much iron is needed by the body and how the body maintains a balance of iron in the body for emergency use in addition to its everyday use. What is the result of extra iron in the diet? How much iron is too much iron?

This last question has been the subject of much heated debate within the horse industry as claims and counter claims are made. Some would argue that any extra iron in the diet i.e. more than 100% RDI could likely result in insulin resistance (IR). Others would claim that not only is there no absolute figure that defines excess, but there are probably no health issues resulting from ingesting “too much iron”.

An exception to this is the case of foals. Foals have died from liver toxicity from too much iron as a result of well-intentioned but misguided attempts to prevent anemia. Their immature gut system is designed to absorb animal protein in the form of milk and iron is absorbed more easily in newborn animals. Iron injections are also potentially risky to horses as they bypass the safety measures in the gut that inhibit excessive iron absorption into the blood stream.

The ‘Great Iron Controversy’ appear to originate from a study conducted by Dr. Brian Nielsen et al in 2012. The study was titled “A potential link between IR and iron overload in browsing rhinoceroses investigated through the use of an equine model” published in the Journal of Zoo and Wildlife Medicine in 2012. The name of the study is perhaps a little ambiguous, on one hand it could be interpreted that iron overload leads to IR whilst on the other hand, IR could lead to iron overload.

Dr Nielsen sought to clarify this in an online posting in April 2013. As quoted by Dr. Nielsen – “The point of our study was to see if the reason iron was accumulating in black rhinos was BECAUSE they were insulin resistant” (

Still, the headlines became “Researchers identify link between Insulin resistance and Iron Overload” penned by various commentators. For those owners concerned about and frustrated by their own horses having IR this seemed like a way they could control the situation. This soon led to the advice that horses should receive no iron supplementation at all and that all feedstuffs should be tested for iron levels before being fed.

So, let us approach this issue armed with peer reviewed scientific knowledge and see what conclusions can be reached.

1. The behaviour of iron atoms and molecules within the body.

Experts are agreed that iron is essential for the survival of the body. It is needed in the transport of oxygen in the blood stream in the erythrocytes (red blood cells). Bacteria are also, dependent upon iron for their survival and this important fact is integral to how the body stores and releases iron.

Iron’s central purpose is to mediate electron transfer at the atomic and molecular level (oxidation and reduction reactions). Iron atoms are incorporated into protein molecules to facilitate enzyme reactions. Iron’s reactivity can also be a potential problem – its ability to donate and accept electrons means it can catalyse hydrogen peroxide into free radicals. Free radicals can cause damage to a wide variety of cellular tissues and can ultimately kill the cell. Iron bound to proteins or cofactors is safe. There are virtually no free iron atoms in the cell since they readily form complexes with proteins. Some of the iron is bound to low affinity complexes and this is termed labile or free iron. It is the iron in these complexes that can cause the damage to cellular structures.

Evolutionary pressures over eons of time have solved the cellular damage problem – all life forms that use iron bind the it to proteins. This allows the cell to benefit from the iron while greatly minimising its ability to do harm. Typically, in a mammalian cell more than 95% of the iron in the cell is bound to stable proteins. To label iron as” dangerous “because of its potential to form radicals is emotive language that questions the ability of the body to cope with this issue. To state that free ionised iron can produce a “chain reaction of destruction” is also an example of highly emotive language. Upon reading such a statement, many people will feel needlessly alarmed and very anxious.

Our advice is to be aware of the fact that iron has this potential under certain conditions, but also have confidence that the body has evolved safe and effective ways to deal with this potential issue.

2. Absorption, storage and elimination of iron in the body.

The body has developed sophisticated and effective methods to control iron intake in the body and to regulate its use and disposal. Iron metabolism is the set of chemical reactions maintaining homeostasis of iron at the cellular and systemic level.

A 500kg horse has approximately 33 grams of iron in its body – 60% of that iron is in the erythrocytes, 20% is in myoglobin in muscles, 20% is in storage and transport in the body and approximately 0.2% is in body enzyme systems. The liver’s store of ferritin is the primary physiologic source of reserve iron in the body. liver storage of iron can fluctuate within a defined level as needed by the body but iron in erythrocytes and enzyme molecules must be kept at a steady optimal level. Because of its potential toxicity, free soluble iron is kept in very low concentrations in the body.

Iron homeostasis in the body is regulated by two processes- systemic iron levels are balanced by the controlled absorption of dietary iron by enterocytes (cells lining the gut wall) and the uncontrolled loss of iron by enterocyte sloughing, sweat, injuries and blood loss e.g. parasitism and bleeding stomach ulcers. A heavily sweating horse can lose up to 500mg iron per day. Mares milk also has reduced iron levels as lactation continues. Systemic iron is continuously recycled by the body.

The absorption of dietary iron is a variable and dynamic process i.e. it is not at a constant level regardless of circumstances. It has the capacity to increase or decrease as needed. Absorption is typically, low-from 5% to 35% depending upon the source of iron and the need for it. Dietary iron absorption in horses is likely to be 15% or less. High levels of iron in soil and feed stuffs does not mean that all or even most of it is absorbed.

Dietary iron is absorbed by the cells lining the small intestine. The cells use specific iron binding transport proteins to move the iron from the gut into the cell. These cells can then either store the iron as ferritin where ferric iron is bound to apoferritin or it can be transported from the cell into the body by ferroportin. Should the enterocyte die and be sloughed into the manure the iron stored in the cell is lost to the body. The enterocyte in response to signals from the liver can increase the amount of ferroportin molecules to increase release of iron from the cell to the body. Iron absorption can also be diminished by the presence of high levels of calcium, zinc and manganese in the diet.

Possible other sources of iron absorption are through volatile fatty acids fermented in the gut- more research needs to be done if this so and the mechanisms by which they operate. Iron may also pass passively through intercellular spaces- under what circumstances does this occur and what percentage is absorbed this way? These are questions that need further research. The general consensus is that by far the majority of iron is absorbed by enterocytes as previously outlined. The body needs a strictly regulated mechanism to control absorption as it cannot afford to have free iron ions circulating unimpeded throughout the body.

The body’s rate of iron absorption appears to respond to a variety of interdependent factors including total iron stores, rate of new erythrocyte production, concentration of haemoglobin in the blood, and the oxygen content of the blood. To suggest that other absorption pathways are unregulated hints at the body being effectively unable to protect itself. There are no scientific peer reviewed studies that prove that this is the case.

The body also absorbs less iron during times of inflammation. This will be discussed in due course.

Most of the iron in the body is stored and recycled by the reticuloendothelial system which breaks down aged erythrocytes. There is no physiologic system that regulates the excretion of iron. In the presence of an efficient and effective absorption control system and carefully regulated use of stored iron the body has not needed to evolve a system of active iron excretion as with other minerals e.g. sodium, potassium, magnesium etc. To put this fact forward as suggesting that the body will just keep on adding iron to its stores is misleading.

Cellular Iron level regulation

Most cell types take up iron through receptor mediated endocytosis through highly specific and controlled enzymatic reactions. It can also enter via plasma membrane divalent cation importers. Neither of these processes are passive transporters of iron from the extracellular site to the intracellular site.

Iron can be stored in ferritin as ferric iron (Fe 3+) which then awaits its future use. Dysfunctional ferritin accumulates as haemosiderin- a chemical that results from iron overload. The ferritin storage pool of iron is much larger than the labile iron pool.

Ferroportin is the only known enzyme that transports ferrous iron (Fe2+) out of the cell. The ferrous iron is then converted to ferric iron to be transported elsewhere. This need to convert iron into its different forms is another safeguard from uncontrolled oxidative reactions that could harm cells.

Hepcidin is an enzyme released from the liver that decreases release of iron from storage in the cell. The expression of hepcidin is tightly controlled and represents the link between cellular and systemic iron homeostasis. It is the gatekeeper that controls the release of iron from enterocytes into the rest of the body. In the case of an iron deficiency the cells actively hold onto their iron preventing the unnecessary synthesis of iron storage proteins and the export of iron from the cell. In summation, there are many enzyme and feedback systems that accurately control iron metabolism for the benefit of the body. It is a highly efficient and sophisticated system designed for survival.

Pathology of iron storage and usage.

When a healthy functioning body becomes diseased, there will be changes noticed in the functioning of the liver. Veterinary pathologists may tell you they see “a lot of’ diseased horse livers”. Their very job description means they are almost always investigating diseased animals.

Pictures of diseased, cirrhotic, blackened livers as evidence of iron toxicity without any contextual detail of that individuals’ history of iron ingestion, concurrent metabolic pathology, duration of illness etc. is frightening and causes anxiety in people who don’t understand the many questions that need to be answered before an explanation can be reached.

Iron Deficiency

Whilst rare in horses, should it occur, it can be due to any of the following factors:

  1. Increased demand for iron which the diet cannot supply.
  2. Increased loss of iron through blood loss.
  3. Nutritional deficiency due to a lack of dietary iron or dietary components that inhibit absorption.
  4. Inability to absorb iron.
  5. Damage to the intestinal lining that reduces the surface area available for absorption.
  6. Inflammation leading to hepcidin induced restriction of iron release.

Iron Overload

  1. It may occur in response to an extraordinary ingestion of iron in the diet that damages the lining of the gut and compromises its ability to regulate iron uptake. Horses that raid feed sheds and eat a large amount of an iron supplement in one sitting might possibly suffer iron overload.
  2. An acute overload of iron can become iron toxicity where the bodies homeostatic mechanisms are overwhelmed to the point where cardiac, liver, renal and brain function are severely compromised. This can result in death. This is most likely the issue that young foals deal with when given iron way in excess of what they need.
  3. Chronic iron toxicity or overload can also be the result of genetic conditions- especially in humans.
  4. Chronic inflammatory conditions may also lead to iron overload through reduced release of iron from storage. The body evolved to deal not only with normal day to day metabolic processes but also to deal with infections caused by bacteria, viruses, spores etc.

 Inflammation and iron storage

Most bacteria also use iron in their metabolic pathways. When the body detects a bacterial infectious process, it reacts by immediately reducing available iron which the bacteria needs to continue to multiply. This is in addition to the other protective responses that come into play. In the short term, the body greatly reduces iron absorption from the gut and also shuts down release from iron storage cells. It is an attempt to starve the bacteria of the iron they need. When the infection has resolved the body returns to its normal processes to harmonise iron homeostasis.

While bacterial invasion is an infectious inflammatory response, there are other occasions within the body where noninfectious inflammatory conditions result. These can include cancer, endocrine disturbances, metabolic diseases, laminitis and autoimmune diseases. The body may not be able to differentiate between the different causes of inflammation but it still sets up the standard response i.e. reduce iron availability to the inflamed tissue. Long term this could lead to build up of iron in the liver SECONDARY to another predisposing cause.

Dr. Nielsen refers to this in his study of black rhinos with IR. “There is NO good evidence that feeding a diet low in iron will correct IR and conversely that excess dietary iron will contribute to IR “.

It would appear that some commentators are blaming iron as the culprit in IR. In fact, the most likely cause of IR is feeding too many calories of the wrong kind i.e. too many sugars and grains combined with inadequate exercise. Chronic iron overload then becomes the symptom of a primary problem initiated by other factors.

Modern lifestyles are increasingly being targeted as responsible for IR in humans, cats, horses, rhinos and possibly some other captive species in zoos as well. Too many calories, too little exercise and stress induced by boredom and frustration in the case of captive animals may all combine to cause this progressive, debilitating and chronic condition. Look to the real needs of horses in terms of dietary intake – ad lib roughage at all times and feed as little grain fed as possible. Ensure that there are adequate and appropriate levels of exercise and mental stimulation for a feeling of wellbeing. Be aware of breed differences that make some equines super-efficient at absorbing calories and also needing more exercise. Horse also need equine companionship and to be able to express natural behaviours.

Iron overload in humans.

There are studies that potentially link IR with iron overload in humans. These studies are directed at human populations that have genetic conditions that intrinsically alter normal iron metabolism. An example of this is thalassaemia- it presents as anaemia and repeated blood transfusions are part of the treatment protocol. The repeated transfusions lead to iron overload and this causes damage to the heart, liver and endocrine systems. Haemachromatosis is an abnormal iron storage disease of humans that results in liver steatosis and pathology. It would not seem reasonable to extrapolate these findings to horses who would have uniquely different causes for IR.

An unpublished paper authored by Dr. E Kellen summarised the following- ” Animals on mineral balanced diets had normal TSI and ferritin levels, and improvement in their insulin resistance, but since other measures were undertaken concurrently (e.g. reduction of NSC in the diet) the effect of mineral balancing per se` COULD not be determined”.

As more research is conducted and more evidence comes to light there may need to be a shift in the way iron supplementation is perceived. To date there has been no overwhelming evidence from multiple studies to suggest that horses are being deleteriously affected by the addition of supplemental levels of iron in the diet. The consensus of scientific opinion is that the increasing numbers of horses and ponies with IR is the result of genetics and modern feeding and husbandry methods. The role that iron probably plays in all of this needs further research but is in all likelihood the RESULT of abnormal metabolism rather than the primary problem.

IR is increasingly impacting the health of humans, horses and cats. The common factor across all three is the type of food being ingested i.e. too much sugars, starches and carbohydrates and less than optimal levels of exercise needed to keep the body healthy.

To study and look at iron in isolation from other minerals in the diet is also not appropriate. Iron levels will affect the rate of absorption of copper, zinc, calcium and manganese. This is why we have never believed in single mineral supplementation. We were the first Australian company to produce a product that contains ALL the necessary minerals in BALANCED ratios.

We at Equilibrium Australia are very aware of our responsibility to the horse industry to produce effective and above all safe nutritional supplements. We do not shy away from this responsibility and can confidently state that our products are safe, effective and can be use confidently used by horse owners and trainers. We have always advocated the Equilibrium Feeding Program which has always stated horses need good quality roughage at all times, as little grains and sugars as possible, and then balance their diet with vitamins and minerals that horse pastures and hays can be often deficient in.

Dr Lex Wills BVSc MACVSc observed the decline in horse health over the many years that he was an equine practitioner. Conventional treatments were either ineffective or only partially solved the problem. Horses were presenting with poor hoof quality, dull coats, infertility, colic, reduced performance, inability to put on weight, laminitis, and Seedy Toe just to name a few. At the same time the recommendations for feeding horses were drifting far away from what horses really needed to consume. There was a strong emphasis on grains and starches and less emphasis on good quality roughage. The resultant diets were mineral imbalanced and often deficient. The results of this change in feeding practice along with reduced exercise culminated in the range of medical issues that vets, owners and trainers were dealing with.

Dr. Lex Wills, through Equilibrium Mineral Mix and B1 Cool Mix began the discussion of how horses should be fed and supplemented with a broad-spectrum mineral and vitamin supplement. There are many, many, appreciative horse owners and happier healthier horses as a result of his genuine compassion and commitment toward improving the diet of horses.

Dr. Jenene Redding BVSc (Hons)

What’s the metal on Iron?

Whilst this post outlines the actions and requirements of iron for the horse, never forget that no mineral or vitamin ever actions in isolation.  Supplementing with a single mineral is often ineffective due to the complex interactions of chemical compounds in the body. Equilibrium and LexveT were designed to overcome this by being a balanced broad-spectrum vitamin and mineral supplement.

What does my horse need iron for?

To transport oxygen from the lungs to organs and tissues around the body. It is absorbed into the blood stream by combining with the protein molecules of haemoglobin and myoglobin. Life as we know it would not exist without this vital element.

A 500kg horse contains approximately 33 grams of iron in its body – 60% of that iron is in haemoglobin in red blood cells, 20% is in myoglobin in muscles, 20% is in storage and transport in the body and approximately 0.2% is in body enzyme systems.

How much iron is needed in the diet?

It is estimated that most horses require 40mg iron per kg of feed/dry matter eaten per day.  Pregnant and lactating mares and foals require approximately 50mg/kg of food ingested.

What are the sources of iron in the diet?

Forage contains approximately 100-250mg iron/kg and grains from 40-50mg/kg.  Free grazing horses also ingest iron from consuming soil attached to plants.  The absorption of iron from these sources into the body is typically low at approximately 5-10%.  A high level of iron in soil and feed stuffs does not mean that all or even most of it is absorbed.

How is iron absorbed by the body?

Iron in the diet is absorbed by the enterocyte cells lining the but wall where they remain in storage until the iron is needed by the body.  The incorporation of iron into the cell is a tightly regulated process as is the release of iron from the cell into the blood stream.  Any stored iron in the enterocyte is lost to the body when the cell dies and is removed in manure.  The absorption of iron by the body is a dynamic and variable process depending upon the bodies needs at that point in time.

How is iron stored in the body?

The body is very effective at scavenging and retaining iron from the regular breakdown of red blood cells.  It is stored in the liver and the reticuloendothelial system to be used again.  In a normal healthy horse the body has very efficient and sophisticated mechanisms to prevent iron overload and iron deficiencies.  It is strongly suspected that horses suffering from chronic inflammatory diseases e.g. Equine Metabolic Syndrome, Laminitis, Insulin Resistance, Gastric Ulceration etc. store extra iron in the liver SECONDARY to a predisposing problem, in other words, elevated iron levels in the liver are a symptom of these conditions.  Feeding less iron to these horses will not resolve the primary problem.

Because the body has a tightly regulated mechanism for the absorption and storage of iron, evolution did not dictate that an excretory pathway was necessary.  In a normal adult horse, the body does not keep on absorbing iron in excess of its needs.

How can an iron deficiency develop?

Iron deficiency is rare in the horse, but when present, is usually seen in horses with blood loss e.g. Gastric Ulcers, Pulmonary Haemorrhages, sever injuries and parasitism. Blood tests can confirm if a horse is anaemic.  Mares milk has reduced levels of iron as lactation proceeds and the foal gains the extra iron needs by starting graze and ingest solids.

Iron is also lost in sweat – a horse in heavy work can lose up to 25-30 litres of sweat in a day which can result in a potential loss of 500mg of iron.

Iron Toxicity

Excessive supplementation of iron especially to young foals can result in death from liver failure.  Accidental overconsumption of an iron supplement by an adult horse can lead to damage to the lining of the gut wall and excess iron enters the blood stream.  This can cause damage to the heart, liver, kidneys and other organs.  Iron fed at recommended rates by supplement manufacturers pose no problems to a healthy horse.  Injectable iron products should be used with great caution as they circumvent the mechanisms that prevent excess iron being absorbed via the digestive system.

Supplementing with iron

Never supplement with any mineral in isolation. Horses need to be fed a balanced and appropriate multimineral/vitamin supplement at all times.

Feeding extra iron in the diet will not increase food intake, red blood cell count, haemoglobin concentration or packed cell volume.  High levels of iron in the diet can decrease serum and liver zinc levels but will have no effect on serum levels of iron, calcium, copper and manganese.

Equilibrium Mineral Mix and B1 Cool Mix can be fed with confidence and safety to all horses.  It is balanced in its mineral composition and supplies what in lacking in most horse’s diets.