Effects of pre-exercise frusemide administration and post exercise anaesthesia on cardiopulmonary and acid-base parameters and blood and plasma volumes in horses exercised supramaximally to fatigue.

The research investigates the impact of pre-exercise frusemide administration and post-exercise anesthesia on different parameters like cardiopulmonary, acid-base, and blood and plasma volumes in horses exercised to a limit. The study found increases in certain parameters due to exercise, but frusemide administration before exercise did not show any effects.

Objective and Experiment Design

• The study aims to examine the effects of administering frusemide (a type of diuretic) prior to exercise, and anaesthetic post-exercise on various parameters related to heart activity, blood and plasma volumes, and blood gases in horses.
• Six horses were randomly assigned to either receive frusemide or an equivalent volume of saline four hours before they were required to exercise on a treadmill.
• The horses were equipped with instruments to measure heart rate, various types of arterial pressures, pulmonary artery pressure, central venous pressure, pulmonary arterial temperature, blood gases, cardiac output. Additionally, the researchers also measure their plasma and blood volumes using Evan’s Blue dye.
• After administration of frusemide or saline, the horses were warmed up for a few minutes and then made to exercise till they were exhausted.

Procedure After Exercise

• Immediately following the exercise, the horses were anaesthetized using detomidine followed by tiletamine-zolazepam.
• They were then moved to a recovery stall where anaesthesia was maintained with isoflurane in 100% oxygen.

Data Collection and Analysis

• Data were collected and analysed using a 2-way ANOVA, a statistical method to determine the variance in a set of data. This was done with repeated measures and any post-hoc differences were identified using the Student-Newman-Keul’s procedure.
• The entire experiment observed increases in various parameters like heart rate, arterial pressures, pulmonary artery pressure, central venous pressure, pulmonary arterial temperature, and blood volumes due to exercise.
• Conversely, they observed decreases in plasma volume, pH, arterial bicarbonate, and base excess as a result of exercise.
• Furthermore, the anesthesia led to marked hypercapnia (an excess of carbon dioxide in the bloodstream), a decrease in heart rate post detomidine administration, and continuous pulmonary hypertension despite the arterial pressure returning to baseline.
• Interestingly, the administration of frusemide produced no significant effects at any point during the study, undermining its perceived utility prior to strenuous exercise in horses.