Urinary indices of horses after intravenous administration of crystalloid solutions.

Saline or glucose solution was infused for approximately 4 hours into six healthy mares in two separate experiments to determine the effect of infusion of crystalloid solutions on fractional excretion (FE) of sodium (Na), chloride (Cl), potassium (K), and phosphorus (P), ratio of urinary creatinine to serum creatinine (UCr/SCr), and ratio of urinary osmolality to serum osmolality (Uosm/Sosm). After intravenous infusion of either saline or glucose solution, FENa, FECl and FEP were significantly increased, whereas UCr/SCr and Uosm/Sosm were significantly decreased. In addition, FEK was significantly increased after infusion of glucose solution. It was concluded that urinary indices were altered by intravenous infusion of crystalloid solutions in healthy mares and that fluid therapy may interfere with the use of these indices for diagnostic purposes.