Renal clearance and fractional excretion of electrolytes over a 24-hour period in horses.

The research investigates the variation of renal clearance and fractional excretion of several electrolytes within a 24-hour period in adult horses. The study found significant changes in the clearance of electrolytes and creatinine over different periods but not in comparison to the entire 24-hour cycle.

Methodology

• The subjects of the study were ten healthy adult horses, provided unrestricted access to water and a complete pelleted ration.
• The horses’ urine was collected and studied in four consecutive 6-hour cycles.
• Blood samples were also taken from the jugular vein at the start and subsequently every six hours for comparison.

Results

• The study found significant variation in the renal clearance of creatinine during the four collections, ranging between 1.474 ml/min/kg of body weight to 2.702 ml/min/kg.
• The average 6-hour clearances of potassium, chloride, and calcium also varied significantly through the collections.
• Significant correlations were found between the mean 24-hour clearance of creatinine and potassium; creatinine and chloride; sodium and potassium; sodium and chloride; and potassium and chloride.
• The confidence interval for 6-hour mean values of fractional excretion of Sodium was between 0.032% to 0.522%; Potassium was between 23.345% to 48.074%; Chloride was between 0.588% to 1.861%; and Calcium was between -0.158% to 6.723%.
• While the fractional excretion of Sodium, Chloride, and Calcium varied significantly within and between individual horses, average values did not differ significantly over time or from the 24-hour mean values.

Conclusion

• The findings reveal significant fluctuations in the clearance of electrolytes and creatinine in different periods but these do not dramatically diverge from the overall 24-hour mean values.
• There were also substantial individual variations in the rates of fractional Sodium, Chloride, and Calcium excretion.]
• The differences over time for urine volume, urine concentrations of creatinine and potassium, urine osmolality, and the ratio of urine-to-plasma urea nitrogen were significant. However, these differences were not substantial when compared to the whole 24-hour cycle.