Effects of exercise, furosemide, blood depletion, and reinfusion on body fluid compartment volumes in horses.

Abstract

High pulmonary blood pressure contributes to exercise-induced pulmonary hemorrhage. The objective of this study was to use bioimpedance spectroscopy to assess body fluid compartment volumes under 3 conditions in 6 racehorses: i) Pre- and post-supramaximal treadmill exercise (control); ii) Exercise 4 hours after furosemide (0.5 mg/kg body weight, IV); iii) Exercise, removal of ~14 L of blood and subsequent reinfusion of the blood. Statistical analysis used linear mixed effects models. Body compartment volumes did not change during the control runs. Total body water (TBW) (= 0.007,= 0.007), extracellular fluid (ECF) (= 0.003,= 0.003), and intracellular fluid (ICF) volumes (= 0.04,= 0.04) decreased pre- and post-exercise following furosemide administration. The ICF trended to decrease (= 0.07) after slow removal of blood. Blood reinfusion increased TBW (= 0.02,= 0.02) and ICF (= 0.005,= 0.005) pre- and post-exercise.