Glycerol hyperhydration in resting horses.

The research examines the effects of administering glycerol-containing solutions to horses, with findings suggesting it induces a state of transient hyperhydration. This is achieved by enhancing the horse’s renal water conservation and stimulating their voluntary water intake.

Experiment Design

• Four horses were utilized for the study, with the each type of treatment administered nasogastrically 1 hour before and 5 hours after.
• The four treatments given in a randomized order were: 1.0 g.kg of glycerol in 8 L of water (G), 8 L water (W), 8 L of 0.9% NaCl solution (S), and 1.0 g.kg of Glycerol in 8 L of 0.9% Nacl solution (GS).

Effect on Chemical Constituents in Blood and Urine

• All treatments triggered mild plasma volume expansion from 3.2% to 5.8% in the first experiment.
• Administering glycerol solutions elevated serum glycerol concentration by approximately 100 times and increased plasma osmolality by around 10 mOsm/kg.
• This also led to increased renal water conservation owing to increased osmole excretion, even though it was not significantly noticeable.
• Conversely, the W treatment lowered plasma and urine osmolality, increased urine production, and reduced renal water conservation.
• The S treatment showed no significant alterations in plasma and urine osmolality, and renal osmole and water excretion.

Effect on Voluntary Water Intake

• In the second experiment where voluntary water intake was observed, horses given the GS treatment drank an extra 5.2 +/- 0.9 L of water during the initial hour after administration of the 8 L solution.
• The other treatments resulted in less than 1.0 L water consumption in the whole 5-hour observation period.

Conclusion

• The results suggest that giving horses a solution of glycerol in saline could induce transient hyperhydration in resting euhydrated horses.
• This is achieved by encouraging renal water preservation and stimulating additional voluntary water consumption.