Texas Equine Veterinary Association

www.texasequineva.com • 7 Electrolytes: When and What to Supplement? Amanda N. Bradbery, Ph.D. is an Assistant Professor in Equine Science in the Department of Animal and Range Science at Montana State University. A native of Virginia, she grew up in the hunter/jumper industry and developed a passion for large animal health and nutrition. Dr. Bradbery went on to pursue a B.S. in Animal and Poultry Science at Virginia Tech hoping for a career in animal nutrition. In 2012, she met her mentor, Dr. Josie Coverdale, at Texas A&M University where she went on to receive her Master of Science in Animal Science in 2014 focusing on the influence of nutraceuticals on joint inflammation and cartilage metabolism. Dr. Bradbery continued her graduate career, completing a PhD in Animal Science at Texas A&M University in 2019 where her research focused on the influence of maternal nutrition on the predisposition of offspring to metabolic disease. Her other research work includes the influence of organic and inorganic trace mineral source on joint inflammation and cartilage metabolism. Amanda.bradbery@ montana.edu Electrolyte supplements are among the most common oral supplements in the equine industry. Like the plethora of electrolyte replacement drinks available for humans, there are many options for electrolyte replacements formulated for horses. It is relatively easy to recognize electrolyte losses from sweat; however, many clients, trainers, and industry professionals remain unsure on when best to replace electrolytes, how to select an electrolyte replacement, and the most appropriate means of supplementation. Garnering a basic understanding of electrolytes, their physiological functions, and their digestion/absorption from the gastrointestinal tract will aid in the selection of products and electrolyte management practices. What are electrolytes? Electrolytes refer to a specific group of minerals. Unique to other macrominerals in the diet, they carry an electrical charge when dissolved in solution. When in solid form, they bind together to form salts but once dissolved into bodily fluids, the weak bonds are broken, and the minerals are present in their electrically charged form known as ions. ese electrolytes include sodium (Na + ), potassium (K + ), calcium (Ca 2+ ), magnesium (Mg 2+ ), and chloride (Cl-; Figure 1). eir charges, whether anionic (-) or cationic (+), play a significant role in their physiological functions. Most clients and industry professionals recognize the role electrolytes play in fluid balance and hydration status; however, their roles are much more expansive. Each electrolyte plays a specific role in various physiological systems, but there is also significant interplay amongst the different ions. Sodium (Na + ), for example, is a large driver of nutrient absorption and is recognized as the primary extracellular cation. It works alongside potassium (K + ), the primary intracellular cation, to regulate sodium- potassium pumps present on most all cells. e sodium-potassium pump functions to stabilize cellular resting membrane potential and regulate cell signal transductions (Figure 2). Although sodium (Na + ) and potassium (K + ) work in conjunction with one another, their absorption from the gastrointestinal tract is quite different. e large majority of dietary potassium (K + ) is absorbed prececally in the small intestine. Sodium (Na + ), however, tends to more closely follow water thus much of the absorption occurs in the cecum and colon. In fact, sodium (Na + ) and chloride (Cl - ) are what drive large intestine water absorption. Sodium (Na + ) the primary extracellular anion, is absorbed in the large intestine creating an osmotic gradient and the potential for water absorption. Calcium (Ca 2+ ) and magnesium (Mg 2+ ) are most well known for their role in bone structure and formation, but that has little to do with their cationic roles as an electrolyte. Muscle contraction and relaxation is a carefully regulated coordination between nerve Amanda N. Bradbery, PhD Bozeman, MT

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