Magnesium Dysregulation.

Magnesium (Mg) is a critical intracellular cation involved in energy metabolism, neuromuscular and cardiac stability, and endocrine regulation of calcium and potassium. In horses, Mg dysregulation is common in gastrointestinal disease, systemic inflammation and critical illness, yet often remains underdiagnosed. Hypomagnesemia contributes to ileus, cardiac arrhythmias, and refractory hypocalcemia or hypokalemia, whereas hypermagnesemia is rarely reported and typically iatrogenic. This review summarizes Mg physiology, regulation, clinical manifestations of Mg dysregulation, diagnostic approaches, and therapeutic strategies, with emphasis on equine-specific considerations.