The Role of Dietary Macrominerals in Equine Hoof Health, Immunity and Inflammation Control

Introduction

Proper nutrition plays a foundational role in equine health, impacting everything from metabolic function to the integrity of hooves, the strength of the immune system, and the regulation of inflammation. Among the key dietary components that contribute to this are macrominerals, which are required by the horse in larger quantities than trace minerals and perform vital structural, metabolic, and regulatory roles. The macrominerals include calcium, phosphorus, magnesium, potassium, sodium, chloride, and sulphur. Today we will explore the significance of each of these macrominerals, focusing on their influence on hoof integrity, immune system support, and inflammation control. By understanding how these minerals operate individually and synergistically within the body, we can design more effective feeding strategies to promote soundness, resilience, and long-term wellness.

A wild Exmoor pony hoof in it's natural state.

Calcium

Calcium is arguably the most recognised mineral in equine nutrition, primarily known for its structural role in the formation and maintenance of bone. However, its function extends far beyond the skeleton. Calcium is a critical component in keratinization, the biological process through which hoof horn is formed. Proper keratin formation requires stable calcium concentrations for epithelial cell adhesion and differentiation, directly influencing hoof wall strength and resilience (NRC, 2007). Inadequate calcium can lead to poor horn quality, increased susceptibility to cracking, and structural defects within the hoof capsule.

In addition to supporting hoof health, calcium plays a central role in immune function. It is involved in the activation of white blood cells, including macrophages and lymphocytes, which depend on calcium signalling to initiate their responses to pathogens. A deficiency in calcium can impair these cellular activities, reducing the horse’s ability to combat infections and inflammation (LeBlanc et al., 2016). Calcium also contributes to vascular function, influencing the dilation and constriction of blood vessels, which has implications for both immune cell trafficking and inflammatory processes. Studies in other species have shown that disruptions in calcium homeostasis may exacerbate chronic inflammatory conditions by impairing cellular communication and cytokine regulation (Clapham, 2007).

In horses, the balance between calcium and phosphorus is particularly important. The ideal dietary calcium to phosphorus ratio is generally accepted as between 1.5:1 and 2:1. Deviations from this balance, particularly if phosphorus intake is excessive, can interfere with calcium absorption and lead to secondary nutritional imbalances that affect hoof growth and systemic health (NRC, 2007). Therefore, while calcium supplementation is critical in some horses, especially those on high-grain or low-forage diets, it must be implemented with careful consideration of the full dietary profile.

Phosphorus

Phosphorus is the second most abundant mineral in the equine body and, like calcium, it is heavily involved in the formation of bone and teeth. Approximately 80% of phosphorus in the horse is stored in the skeleton. Its role in hoof health is more indirect than calcium but no less important. Phosphorus is a component of phospholipids, which form the cellular membranes essential for the structure and function of living tissue, including that of the hoof dermis and epidermis (Pagan, 1999). Deficiency in phosphorus can disrupt cell turnover and hoof tissue regeneration, leading to soft, brittle hooves that are prone to injury and infection.

From an immune standpoint, phosphorus is a core constituent of nucleic acids (DNA and RNA) and energy metabolism, most notably adenosine triphosphate (ATP), the energy currency of the cell. A horse’s immune cells require large amounts of energy during times of infection or inflammation, and phosphorus deficiency can limit their metabolic capacity (Lofstedt, 2007). Moreover, inflammatory mediators and cytokines are synthesized and transported via phosphorus-dependent processes, highlighting its importance in modulating immune responses and reducing the duration or intensity of inflammatory episodes.

It is important to consider the source of phosphorus in the equine diet. While forage contains some phosphorus, cereal grains and by-products such as wheat bran are much richer sources. However, excessive or poorly balanced phosphorus intake can impair calcium absorption and create skeletal abnormalities or metabolic disturbances. Young, growing horses and lactating mares have higher phosphorus demands, but supplementation in mature horses should be approached conservatively to avoid disrupting the delicate mineral balance that supports not only hoof health but immune and inflammatory functions as well (NRC, 2007).

Magnesium

Magnesium is often overlooked in equine diets, yet it is a key cofactor in over 300 enzymatic reactions and plays a major role in cellular energy production, muscle relaxation, and nerve function. From the perspective of hoof health, magnesium is essential for protein synthesis, including the production of keratin, the fibrous protein that constitutes the bulk of the hoof wall. Horses deficient in magnesium often exhibit signs of hoof deterioration, including cracking, flaking, and slow growth (Warren and Kline, 2012). Adequate magnesium levels support the strength and elasticity of the hoof horn by stabilising the structures within the laminae and hoof wall.

Magnesium is also critically involved in the modulation of the immune system. It regulates the activity of natural killer cells and influences the production of inflammatory cytokines such as interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) (Rude and Gruber, 2004). Low magnesium levels have been associated with increased levels of systemic inflammation and oxidative stress, not only in horses but in multiple mammalian species. In horses, magnesium deficiency is frequently associated with stress, anxiety, and heightened reactivity, all of which may influence immune status indirectly by raising circulating cortisol levels and suppressing immune function (Friend, 1991).

In practical feeding terms, magnesium is typically found in pasture, hay, and grains, but levels can vary widely depending on soil content and forage type. Horses under high stress, those in intense work, and those with metabolic conditions such as equine metabolic syndrome (EMS) may benefit from supplemental magnesium to support both hoof health and immune regulation. Care must be taken, however, as excessive magnesium intake can lead to diarrhoea and interfere with the absorption of other minerals such as calcium and phosphorus (NRC, 2007).

Potassium

Potassium is the most abundant intracellular cation in the equine body and plays a key role in nerve transmission, muscle contraction, and fluid balance. Its direct influence on hoof health is less well documented than other macrominerals, but its systemic roles strongly affect tissue hydration and vascular integrity, both of which are essential for the growth and maintenance of healthy hooves. Proper circulation within the hoof capsule ensures the delivery of oxygen and nutrients necessary for keratinocyte proliferation and horn production. Potassium supports the maintenance of cellular osmotic pressure, enabling cells in the hoof to remain hydrated and functional.

From an immune perspective, potassium influences the electrical gradient across cell membranes, which is crucial for the activation of immune cells. Altered potassium balance can impair the ability of immune cells to respond to threats or initiate appropriate inflammatory responses. Additionally, potassium is essential for acid-base regulation in the body, and disruptions in pH can alter enzyme function and contribute to inflammatory conditions, especially in the digestive tract where systemic inflammation may begin (Geor et al., 2013).

Most horses on pasture or consuming good quality hay will meet their potassium requirements, as grass is a rich source. However, horses that sweat heavily, such as those in endurance or eventing, may lose significant potassium through sweat and require supplementation in the form of electrolyte replacements. Potassium imbalances can also occur in horses with chronic diarrhoea, renal issues, or prolonged anorexia. While toxicity is rare, particularly because excess potassium is efficiently excreted, careful attention should be paid to its intake in horses with insulin resistance or metabolic syndrome, where potassium transport can be impaired.

Sodium

Sodium is essential for nerve impulse transmission, muscle function, and fluid balance, and it plays a supportive role in tissue perfusion and hydration, including in the sensitive laminar tissues of the hoof. A sodium deficiency, though not directly linked to poor hoof structure in the literature, can indirectly compromise hoof quality through dehydration, impaired blood flow, and decreased nutrient transport. Sodium influences the movement of water between body compartments and is crucial for maintaining vascular tone, which in turn affects circulation to the extremities including the hooves (Pagan, 1999).

The immune system is also dependent on sodium for proper function. Sodium ions are involved in the activation of immune cells, particularly during the inflammatory response. An appropriate sodium balance ensures that immune cells can migrate to areas of infection or injury and perform their functions effectively. Furthermore, sodium influences the production of reactive oxygen species (ROS) and nitric oxide, both of which are used by the immune system to combat pathogens but can cause tissue damage if not tightly controlled (Gombart et al., 2020).

In practical terms, sodium is the most commonly deficient macromineral in equine diets, especially in horses that work or sweat regularly. This is because natural forages contain very low levels of sodium, and unlike potassium, the horse has a limited ability to store it. Therefore, salt (sodium chloride) should always be provided, either as free-choice blocks or mixed into the feed. Sodium deficiency can result in poor performance, muscle cramping, and even colic. Ensuring consistent sodium intake not only supports general health and hydration but also contributes indirectly to maintaining hoof vascularity and immune efficiency.

Chloride

Chloride is the major anion that balances sodium in the extracellular fluid, and it is essential for maintaining electrolyte balance, acid-base homeostasis, and osmotic pressure. Chloride combines with hydrogen to form hydrochloric acid, which is vital for digestion and the absorption of nutrients including amino acids that contribute to keratin formation in the hoof (NRC, 2007). While chloride is not traditionally associated with hoof integrity, its function in nutrient assimilation and fluid distribution within the body can indirectly support healthy hoof growth and resilience.

In the immune system, chloride plays a role in the phagocytic activity of white blood cells. Neutrophils, which are frontline immune cells, use chloride ions as part of the respiratory burst needed to kill invading microbes. Without adequate chloride, this process is compromised, potentially leading to weaker immune defences and prolonged inflammation (Halliwell and Gutteridge, 2015). Inflammation that is not well regulated can damage tissues, including those in the hoof such as the sensitive laminae, particularly in systemic inflammatory conditions like sepsis or laminitis.

Chloride is lost through sweat along with sodium and potassium, particularly in horses performing intense exercise or those exposed to high temperatures. Commercial electrolyte supplements are designed to replace these losses and often contain chloride in combination with sodium and potassium. As with sodium, inadequate chloride intake can lead to metabolic disturbances and reduced hydration, both of which compromise tissue function and may indirectly affect hoof health.

Sulphur

Sulphur is a component of certain amino acids namely methionine and cysteine, which are crucial for keratin synthesis, the primary structural protein of the hoof. The strength, hardness, and elasticity of the hoof wall depend heavily on sulphur cross-links within the keratin structure. Without sufficient dietary sulphur, either directly or via sulphur-containing amino acids, the quality of the hoof horn may deteriorate, becoming brittle, soft, or slow to grow (Bailey et al., 2000).

Sulphur also plays a central role in detoxification and inflammation control. It is a component of glutathione, one of the most powerful antioxidants in the body, which protects cells from oxidative stress and reduces inflammation. Inflammatory diseases such as laminitis, arthritis, and allergic reactions involve the generation of free radicals that damage tissue. Sulphur containing compounds help neutralize these radicals, thereby protecting the hoof and other tissues from inflammatory damage (Goff, 2000).

Good sources of sulphur include high-protein feeds such as alfalfa, soybean meal, and linseed. Biotin supplements often contain added methionine to improve hoof growth, based on its sulphur content. However, excessive supplementation can be problematic. Overfeeding protein or sulphur-containing compounds can lead to excess nitrogen and ammonia in the gut, potentially disrupting the microbial balance and promoting inflammation. Therefore, while sulphur is essential, it must be delivered in balance with other dietary components.

Conclusion

Macrominerals form the cornerstone of equine nutrition and are vital for maintaining hoof strength, immune competence, and inflammatory balance. Each mineral plays multiple roles in the body, with complex interconnections that influence structural development, metabolic efficiency, and immune responsiveness. Calcium and phosphorus provide the building blocks for bone and hoof keratinization, while magnesium supports nerve function, enzyme activity, and inflammation control. Potassium, sodium, and chloride work together to maintain hydration, acid-base balance, and vascular health, all of which impact hoof perfusion and systemic immune response. Sulphur, through its presence in key amino acids and antioxidants, directly supports hoof horn quality and reduces the risk of inflammation-related tissue damage.

Meeting the daily foundational nutritional requirements for a horse will lead to strong healthy feet.

Achieving and maintaining the right balance of macrominerals is crucial. Too little can lead to poor hoof quality, reduced immune defence, and chronic inflammation, while too much or improper ratios can interfere with the absorption of other nutrients and create metabolic stress. Horses with specific health conditions, those under heavy workload, or those with compromised hoof quality may benefit from targeted supplementation, but any changes to the mineral profile of the diet should be made with careful consideration and preferably under veterinary or nutritional guidance.

Ultimately, understanding the broader roles of macrominerals in the equine body empowers owners, farriers, and vets to work together to support hoof health from the inside out.

References

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