Effect of endotoxin administration on body fluid compartments in the horse

Plasma volume, extracellular fluid volume (ECFV), and total body water (TBW) were measured before and after endotoxin (Escherichia coli) administration in 6 conscious adult horses. Evan's blue dye, sodium thiocyanate, and antipyrine were the test substances used to estimate plasma volume, ECFV, and TBW, respectively. Pharmacokinetic analysis of plasma concentration vs time was used to determine changes in body fluid compartments. The pathophysiologic effects of endotoxin were monitored by clinical evaluation, blood chemical changes, and blood gas determinations. All horses became dyspneic within 15 minutes of endotoxin administration and clinical signs of colic were evident 30 to 45 minutes after endotoxin administration. After endotoxin administration, serum glucose and creatinine concentrations were significantly (P less than 0.05) elevated, and all horses became hypoxic and developed marked metabolic acidosis, and plasma volume decreased approximately 15% (P less than 0.05). A significant change in ECFV or TBW during the 300-minute experimental period was not observed.