Effect of feed deprivation on daily water consumption in healthy horses.
Authors: Freeman David E, Mooney Alexandra, Giguère Steeve, Claire Jami, Evetts Chloe, Diskant Patricia
Journal: Equine veterinary journal
Summary
# Editorial Summary Feed deprivation triggers a dramatic and immediate collapse in voluntary water intake, reducing consumption to approximately 16% of levels observed during normal feeding—a finding with significant implications for managing horses undergoing pre-operative fasting, recovering from illness, or experiencing appetite loss. This randomised crossover study, conducted over eight days in eight Thoroughbred geldings, demonstrated that the suppression of drinking persisted throughout the deprivation period and was accompanied by laboratory markers of mild dehydration by day 4, including changes in packed cell volume, total plasma protein and plasma osmolality. The research highlights a critical gap between current water intake guidelines (which are based on fed horses) and the actual physiological behaviour of horses with reduced or absent feed consumption, suggesting that existing recommendations substantially overestimate requirements in horses that are fasted or anorexic. For practitioners managing pre-surgical cases, hospitalised horses or those with compromised appetite, these findings underscore the need for more cautious fluid management protocols and heightened vigilance for dehydration, particularly beyond the first few days of deprivation. Although the study did not measure total body water compartments or trace the fate of water and electrolytes through faecal and urinary routes, it provides essential baseline data demonstrating that feeding status is a primary driver of drinking behaviour—knowledge that should inform clinical management strategies whenever horses cannot or will not eat normally.
Read the full abstract on PubMed
Practical Takeaways
- •Horses denied feed for any reason will consume dramatically less water (~84% reduction) and risk dehydration within days—account for this when horses are fasted for medical procedures or competitions
- •Standard water consumption recommendations based on fed horses are unreliable for animals with reduced or absent feed intake; adjust hydration management accordingly
- •Monitor clinical signs of mild dehydration (PCV, TPP changes) in fasted horses, as voluntary drinking alone will not meet normal water requirements
Key Findings
- •Feed deprivation immediately and persistently reduced water consumption to approximately 16% of fed values
- •Laboratory evidence of mild dehydration was present by day 4 of feed deprivation
- •Current water intake guidelines based on fed horses may not apply to feed-deprived horses
- •Feed consumption has a marked effect on water requirements in healthy horses