Rehydration fluid temperature affects voluntary drinking in horses dehydrated by furosemide administration and endurance exercise.
Authors: Butudom Prawit, Barnes Donna J, Davis Matthew W, Nielsen Brian D, Eberhart Susan W, Schott Harold C
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Following strenuous endurance exercise combined with pharmaceutical dehydration, horses demonstrated a marked preference for rehydration fluids at near-ambient temperature (20°C), consuming significantly more total fluid at this temperature (19.9 L) compared to both cold (10°C: 14.7 L) and warm (30°C: 16.3 L) options. In this controlled trial involving six young horses dehydrated to 4–5% body weight loss via furosemide and 30 km treadmill work, immediate post-exercise saline intake (first 5 minutes) showed no temperature preference, yet voluntary water consumption during the 20–60 minute recovery window revealed clear temperature sensitivity, with warmer fluids (20–30°C) eliciting significantly greater intake than cold water. Whilst the cooling effect of ingested fluid accounted for less than 5% of total exercise-generated heat dissipation, the researchers hypothesised that oropharyngeal thermoreceptor satiation from very cold fluids may have suppressed continued drinking despite ongoing dehydration. For practitioners managing endurance and competition horses, this finding suggests that offering rehydration solutions at ambient stable temperature rather than chilled may encourage more complete voluntary rehydration during critical early recovery windows, potentially supporting more efficient restoration of plasma volume and cardiovascular stability without requiring active cooling protocols.
Read the full abstract on PubMed
Practical Takeaways
- •Offer rehydration fluids at near-ambient temperature (around 20°C/68°F) to maximize voluntary drinking in dehydrated, post-exercise horses
- •Avoid very cold fluids (10°C) during recovery as they may trigger early satiation through oropharyngeal cooling, limiting total rehydration
- •Do not rely on fluid temperature as a primary mechanism for core temperature reduction in hyperthermic horses; focus instead on other cooling methods
Key Findings
- •Horses offered 0.9% NaCl at 20°C during initial 5-minute recovery drank similar amounts (12.3±2.1L) as cooler (10°C) or warmer (30°C) temperatures (p>0.05)
- •Between 20-60 minutes of recovery, water intake at 20°C (7.7±0.8L) and 30°C (6.6±1.2L) was significantly greater than at 10°C (4.9±0.5L, p<0.05)
- •Total fluid intake was greatest at 20°C (19.9±2.5L) compared to 10°C (14.7±2.5L, p<0.05)
- •Metabolic heat transferred to ingested fluid accounted for at most 5% of heat generated during endurance exercise