Magnesium in Horses

Presentation Description / Summary: Magnesium (Mg) is a pleiotropic factor with a multitude of functions, including membrane ion transport, energy generation and use, nucleic acid synthesis, neuromuscular modulation, cell proliferation, and calcium (Ca) homeostasis. It is essential for cardiovascular, respiratory, neurologic, renal, gastrointestinal, endocrine, reproductive, and skeletal physiology. Unlike Ca, Mg is not under a tight homeostatic control and its blood concentrations depend on intestinal absorption, renal excretion, and bone exchange. Hypomagnesemia is poorly recognized, common in critically ill equine patients and it has been linked to mortality. Measurement of Mg concentrations has been infrequent in equine practice but should be considered due to the negative consequences of Mg depletion. When possible, it is also recommended to measure ionized or active Mg (Mg2+), particularly in critically ill patients. The main use of Mg in equine practice has been the enteral administration of Mg sulfate (MgSO4, Epson salt) in horses with large colon impaction. However, Mg therapy may be indicated in horses and foals with hypomagnesemia, hypocalcemia, hypophosphatemia, feed restriction, dyslipidemia, prolonged fluid therapy, and acute brain injury. Mg supplementation may have clinical applications for a number of chronic equine disorders, including hypocalcemia, energy dysregulation and neuropathies. Acute hypermagnesemia can alter endocrine, cardiovascular, and neurologic functions in horses. Due to its pleiotropic properties, intravenous administration of MgSO4 has become a nefarious practice by horse owners and trainers. It is important for equine practitioners and specialists to understand biological, clinical and therapeutic aspects of Mg. Deficiency of this ion could impact outcome.

Learner Outcomes: Raise awareness on disorders of magnesium in horses Discuss disorders of magnesium regulation in horses Discuss the value of magnesium therapy in acute and chronic equine conditions