Minerals And Electrolytes

Electrolytes and minerals

Minerals and electrolytes in horses are elements (atoms) that are NOT carbon, hydrogen, oxygen and nitrogen. Instead, they include the macro-minerals of calcium, phosphorus, potassium, magnesium, sodium, chloride and sulfur. They also have the micro-minerals (trace minerals) of copper, zinc, selenium, iron, and others.

The most common source of minerals is groundwater and food grown on the ground. Overproduced soil yields poor crops, so most hay is grown in supplemented soil (fertilized), including minerals. However, many horse owners neglect their pastures and do not test and resupply the fields with the needed minerals for healthy growth and continuous mineral supply for their horses.

Most horse owners also supply a source of salt. The common salt lick has sodium and chloride, which are essential for life. Some add other minerals into a “sweet lick” or “red salt lick,” which contains different minerals but also molasses and high fructose corn syrup. The best salt source is mined from a salt deposit such as Himalayan or Redmond salt because these have an assortment of macro and micro minerals.

A mineral is an atom or element with a nucleus of protons and neutrons surrounded by spinning electrons. Remember basic chemistry? You might remember that an atom can gain or lose electrons. When a mineral gains or loses an electron, then the mineral becomes an electrolyte. Here is an example. Sodium (Na) can lose an electron and become a positively charged atom called Na+.  Chloride can gain an electron and become a negatively charged atom called Cl-. These charged atoms (also known as ions) become attracted to each other because of their opposite charge and become an electrically balanced molecule called NaCl – salt.

Horses constantly lose minerals in the form of electrolytes in the urine and sweat. However, through a highly regulated process called chelation, horses absorb the minerals from the diet back into their body in the exact amounts they need and will not exceed this. Horses also try not to lose minerals. An example is iron, found in the red blood cell within a protein called hemoglobin. They lose this iron only through blood loss, so absorbing additional iron occurs only when needed.

Adding an electrolyte source for almost all horses is unnecessary. As we see in our sports drinks, most supplemental electrolytes have added sugar (see the ingredient list in the top image) to aid absorption. Add electrolytes when the horse works hard, usually in the heat with exercise, causing excessive sweating. In addition, a condition called “thumps” or synchronous diaphragmatic flutter occurs where the horse “hiccups” or sharply inhales with every beat of the heart. Adding electrolytes by intravenous injection resolves this immediately.

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Minerals are elements (see the periodic table of elements, also known as atoms) required by horses to perform necessary functions in the body. For example, iron attaches oxygen to the hemoglobin protein within the red blood cell. The horse cannot make minerals; therefore, they are considered essential for life and consumed in their food. The five major minerals in humans are calcium, phosphorus, potassium, sodium and magnesium. The remaining minerals are called trace elements and include sulfur, iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine and selenium.

Calcium (Ca) and phosphorus (P) are essential in bone formation, especially in young, growing horses. While a calcium deficiency is almost impossible, in extreme cases, phosphorus deficiency can cause many problems. Remember ATP in the mitochondria? The “P” in ATP is phosphorus. On the flip side, too much phosphorus prevents calcium absorption and will cause soft bones (rickets). Adding dicalcium phosphate prevents rickets and is added to grain mixes. Another term for rickets was “Miller’s Disease” when, a long time ago, grains were fed to horses by the milling industry. Today, wheat byproducts and grains are in horse feed and adding dicalcium phosphate prevents rickets. Nutritional Secondary Hyperparathyroidism (big head disease, brain disease, miller’s disease) is a nutritionally caused calcium deficiency avoided by maintaining the amount of calcium in food slightly higher than the phosphorus.

Horse owners often add magnesium (Mg) to calm their horses. A deficiency will cause hyper-irritability, tetany, glazed eyes and collapse, so it makes sense to add magnesium to calm the excitable horse. However, the primary cause of magnesium deficiency is the blocked absorption caused by excessive feeding of calcium or phosphorus. Horses are being fed excessive phosphorus from grains, wheat bran and wheat middlings and more calcium and phosphorus are added with dicalcium phosphate to counter the high phosphorus. Then it would be logical that the horse will become deficient in magnesium. Therefore, removing grains with high phosphorus content and the added dicalcium phosphate may be more rational than adding magnesium. Maybe this is why removing grain from the diet causes horses to settle down quickly, within days.

Potassium (K) – A deficiency in this element is uncommon in horses. Still, an excess caused by a genetic mutation in Quarter Horses will produce hyperkalemic periodic paralysis (HYPP), a disease of muscle weakness with fasciculations.

Sodium (Na) and chloride (Cl) (salt – NaCl) – These elements are everywhere and are necessary for life in all systems within the horse’s body. It is offered free choice to horses. I have rarely seen deficiencies, but occasionally, a horse overeats salt and devours a salt block in little time, causeing the horse to drink large amounts of water and urinate a flood of water. I call this a kidney medullary washout, requiring the normal kidney gradient re-establishment.

Iodine (I) – Too much or too little iodine in the diet will cause goiter, a term used to describe an enlarged thyroid gland. Another cause of goiter has an unknown cause (idiopathic). In all cases I have seen, there is usually being fed a supplement with seaweed, specifically kelp, which is high in iodine. Removing this supplement reduces the goiter to normal size. The horse shows no ill effects from a deficiency or an excess of iodine.

Iron (Fe) – The information about iron is extrapolated from humans and other animals and is presumed to be the same. Iron is conserved by the horse with very little loss, except for severe bleeding. Because of efficient mineral conservation, iron absorption occurs only when needed. An iron deficiency is called anemia which leads to exercise intolerance. Excess iron supplementation (injected, fed or in the environment) can become lethal by replacing other minerals and causing tissue weakness (hemochromatosis, liver disease, diabetes). Older horses may have higher iron levels due to chronic excess iron storage. There is a blood test to determine iron levels in the horse.

Copper (Cu) – Deficiencies are not common in horses. It may be part of the development of osteochondrosis in growing foals. There is no known toxicity level in horses.

Zinc (Zn) – Deficiencies are not common, but reported toxicity occurs in fields located near smelters of metals.

Manganese (Mn) – This is not an essential element. In one report, a hay field received excessive limestone, and the hay then became low in manganese. The subsequent foals born from mothers eating this hay had severely deformed limbs. However, it is rare to have a deficiency or toxicity in horses fed good quality pasture and hay.

Selenium (Se) – This mineral is low in some soils, and a deficiency can occur in newborn foals as muscular dystrophy and is called “White Muscle Disease.” They are often too weak to stand or swallow and die of starvation. Testing and then supplementing the mare before birth will avoid this disease. Deficiencies in horses older than newborns have not caused problems, though most commercial feeds add selenium routinely. Toxicity with selenium is more of a concern in the western states of America (Wyoming, Colorado, South and North Dakota, Montana, Utah and Nebraska) because some plants store selenium which the horse eats. Horse owners living in these areas know this and avoid these plants. Toxicity causes “Blind Staggers,” which may include lethargy, unsteady gait, difficulty breathing, diarrhea, increased pulse, respiration and temperature and death. While toxicity is not common in commercial feeds, it is a potential threat to all horses eating commercial mixes. With great sadness, my friend watched 12 polo ponies die a terrible death in front of him after all the horses received an IV medicine made with an accidental tenfold amount of selenium. Use care when feeding anything with selenium supplementation.


Electrolytes are elements that, when added to a solvent like water, either lose or gain an electron, becoming a charged ion. For example, a positively charged electrode placed in one end of the salt water, and a negatively charged electrode placed in the other end causes an electric current when the charged ions moving through the water to either gain or lose an electron and finally become balanced (no charge). The movement of electrons between ions is how the nerves, muscles and everything else works in all animals, including your horse.

The common elements in horses that can become “charged” include sodium (Na+), chloride (Cl-), potassium (K+), calcium (Ca++), magnesium (Mg++), carbonate (HCO – – –) and phosphate (PO4 – –). After the elemental abbreviation, the + and – signs mean that the element is in the charged or ionic state. Why is this important in horses? Because the only way to get these elements into a charged state is to keep them apart and separated. The separation of charges is an activity every cell in the body expends energy on every moment of the horse’s life. It is like two lovers, each in separate rooms; there is great potential but a wall between them. When signaled, an action occurs through this created current by the movement of ions across the wall. Every action made in the body is because a potential between 2 charged ions creates an electric current through an opening in the wall between them. Such actions include contracting a muscle, sending a nerve transmission, a heartbeat, a thought, scratching an itch, and everything else in life. The ECG (electrocardiogram) measures these currents of your heart.

A cell pump forces the charged elements into the spaces outside the cell (extracellular space) or inside the cell (intracellular space). Na+ is primarily outside the cell, and K+ is mainly inside the cell. Their concentrations are precise in the horse, with the gradient between the two unchanging until needed. The same is true with all ions creating potentials across solid membranes. Whenever ions are allowed to come together, the potential changes into a current, and the action occurs.

The main causes of electrolyte loss in horses are extreme sweating and diarrhea. If your horse isn’t sweating (too cold, not exercising) or doesn’t have severe diarrhea, then there is no need to supplement with these elements because there are plenty of these elements in the food they eat. In addition, almost every electrolyte supplement for horses contains sugar, which is unnecessary to add to the diet.

Some signs of electrolyte deficiency in horses include muscle cramping (not exertion myopathy, which is a genetic disorder), muscle exhaustion (depleted calcium reserves) and synchronous diaphragmatic flutter (“Thumps” “Hiccups”).

HYPP is an electrolyte imbalance from a genetic mutation occurring in heavily muscled Quarter Horses within a family line. As a result, the potassium on the inside of the cell and the sodium on the outside can freely cross the muscle cell wall, eliminating the potential to thoughtfully make a current and muscle contraction.

Thumps occur in dehydrated horses when the potential between ions is accidentally triggered by the electric current of the heartbeat across the gap between the heart and the phrenic nerve lying across the heart on its way to the diaphragm. The diaphragm contracts synchronously with the heartbeat creating a jerk of the diaphragm (a hiccup) ranging from mild to severe thumping. Thumps is cured with rehydration using electrolyte solution IV.


All minerals need to bind to a ligand (a group of molecules that include amino acids) through a chelation process to be absorbed across the gut wall. Chelation is the regulatory process that prevents the over-absorption of minerals. A needed mineral causes the production of the ligand, and chelation of that mineral is allowed to occur. Chelation provides for the controlled absorption of that mineral through the gut wall.

My concern about feeding packaged minerals chelated in a factory is 1) does the chelated mineral make it past the acid bath of the stomach, and 2) if it does get to the small intestine, is the chelated mineral bypassing this regulation process? In other words, is adding a chelated mineral as a supplement effective? Is adding chelated minerals necessary if horses do not show a mineral deficiency? But more importantly, if horses are chronically protein deficient, is it a mineral deficiency we see or is what we see secondary to an inability for the horse to chelate because of the absence of the needed amino acids?

A horse licking a salt block

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