Effects of Different Oral Doses of Sodium Chloride on the Basal Acid-Base and Mineral Status of Exercising Horses Fed Low Amounts of Hay.
Authors: Zeyner Annette, Romanowski Kristin, Vernunft Andreas, Harris Patricia, Müller Ann-Marie, Wolf Carola, Kienzle Ellen
Journal: PloS one
Summary
# Editorial Summary Current salt supplementation guidelines for moderately exercised horses may inadvertently compromise acid-base balance, particularly at higher doses. This 2017 study examined how different oral sodium chloride supplementation levels (0, 50 or 100 g daily) affected the blood and urine chemistry of six warmblood mares fed a forage-restricted diet (1 kg hay per 100 kg bodyweight daily), with measurements taken over a 15-day period following a 3-week adaptation phase. The 100 g dose induced mild metabolic acidosis with reduced blood pH and base excess that persisted throughout the study, whilst the 50 g dose—aligned with most current recommendations—resulted in compensated acidosis characterised by altered base excretion and urine density despite normal resting blood pH; notably, both supplemented groups demonstrated high urinary sodium and chloride losses, indicating substantial renal excretion of the supplemented salt. For equine practitioners managing horses in moderate work, these findings suggest that whilst the commonly recommended 50 g daily salt dose appears safer than higher intakes, it still produces measurable acid-base shifts that may warrant monitoring, particularly in horses with marginal mineral status or those fed characteristically low-forage diets.
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Practical Takeaways
- •Current salt supplementation recommendations (50 g/day) for moderately worked horses may cause compensated acidosis; practitioners should monitor acid-base status in horses receiving these doses, particularly those on forage-restricted diets
- •High renal excretion of supplemented salt suggests much of the added NaCl is wasted; consider whether current dosing is necessary or whether lower amounts with better timing would be more efficient
- •Horses on low-forage diets receiving salt supplementation warrant closer attention to acid-base balance, as the combination may compound metabolic challenges
Key Findings
- •100 g/day NaCl supplementation induced mild metabolic acidosis (reduced blood pH and base excess), while 50 g/day resulted in compensated acidosis in moderately exercising horses
- •Both 50 g and 100 g NaCl doses increased urinary sodium and chloride fractional clearance, indicating high renal excretion of supplemented salt
- •NaCl-induced acidotic effects persisted consistently over a 2-week adaptation period without resolution
- •Apparent sodium digestibility was 60-62% while chloride digestibility exceeded 94%, suggesting differential mineral handling