Effect of Feed Intake on Water Consumption in Horses: Relevance to Maintenance Fluid Therapy.
Authors: Freeman David E
Journal: Frontiers in veterinary science
Summary
# Editorial Summary: Feed Intake and Water Requirements in Equine Maintenance Fluid Therapy Freeman's 2021 review addresses a fundamental challenge in equine medicine: determining appropriate maintenance fluid volumes for horses unable to eat or drink, particularly those with suspected gastrointestinal compromise. Current IV fluid protocols are based on recommendations derived from fed horses, yet this approach fails to account for the enterosystemic cycle—the critical interdependence between gastrointestinal water secretion and extracellular fluid dynamics that supports normal digestive function. By examining the relationship between oral feed intake and voluntary water consumption, Freeman demonstrates that fasted horses exhibit significantly reduced drinking behaviour and consequently lower absolute water requirements than their fed counterparts, rendering standard maintenance calculations potentially excessive and counterproductive. Adjusting fluid therapy protocols downward for non-fed patients offers meaningful clinical benefits: reduced IV volumes decrease infusion workload, lower pharmaceutical costs, and critically, minimise the risk of overhydration—a particular concern in horses with compromised intestinal function where fluid redistribution poses genuine risk. For practitioners managing colic cases or other conditions necessitating feed and water restriction, this evidence supports a more nuanced, individualised approach to maintenance therapy that acknowledges the physiological reality that a fasted horse's fluid needs differ substantially from a normally feeding animal.
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Practical Takeaways
- •Reduce maintenance fluid rates when horses are not being fed, as their actual water needs are lower than standard recommendations based on fed horses
- •Adjust fluid therapy protocols based on gastrointestinal function status to avoid overhydration complications and reduce treatment costs
- •Consider the enterosystemic cycle when calculating fluid needs—water requirements are not static but depend on digestive activity
Key Findings
- •Maintenance fluid therapy recommendations based on fed horses may overestimate water needs in fasted horses
- •Water consumption is interdependent with feed intake through the enterosystemic cycle
- •Adjusting maintenance fluids to lower requirements in non-fed horses reduces volume, cost, and overhydration risk
- •Current IV fluid protocols may not account for reduced gastrointestinal water demands in horses denied feed and water