Influence of cyclooxygenase inhibitors on furosemide-induced hemodynamic effects during exercise in horses.

This study was designed to investigate if the impact furosemide has on blood flow during exercise in horses could be counteracted with the use of cyclooxygenase inhibitors. The results indicated that the combination of furosemide and either of the cyclooxygenase inhibitors tested were able to return certain metrics of cardiovascular performance back to control levels during exercise but did not affect the other examined variables.

Objective of the Study

The purpose of this research was to understand whether the hemodynamic effects (relating to the flow of blood within the organs and tissues of the body) caused by furosemide, a drug used to prevent exercise-induced pulmonary hemorrhage in horses, could be counteracted by using cyclooxygenase inhibitors, a class of drugs that reduce inflammation.

Methodology

• Four different treatments were tested, each administered to five horses 4 hours before a treadmill exercise at two different speeds.
• The control group received a 10ml quantity of saline solution, administered intravenously.
• One group received furosemide alone, dosed at 1mg/kg of body weight, intravenously.
• The two other groups received furosemide combined with either phenylbutazone (a nonsteroidal anti-inflammatory drug) or flunixin meglumine (another nonsteroidal anti-inflammatory drug).

Results

• The researchers found that when administered alone, furosemide reduced both mean right atrial pressure and mean pulmonary artery pressure during exercise.
• However, when furosemide was combined with either of the two cyclooxygenase inhibitors, these two pressure metrics were restored to control levels.
• In terms of other variables examined, such as plasma lactate concentration, pulse rate, mean carotid artery pressure, oxygen consumption, carbon dioxide elimination, and cardiac output, no changes were observed under any of the treatments.
• Even during the recovery period post-exercise, these metrics remained unaffected by the treatments barring a decrease in mean right atrial pressure when horses were administered furosemide alone or combined with phenylbutazone.

Conclusion

From the results, it can be concluded that the hemodynamic effects induced by furosemide during exercise in horses were partially reversed by co-administration with cyclooxygenase inhibitors. However, only select parameters, namely mean right atrial pressure and mean pulmonary artery pressure, were positively affected while other physiological variables remained relatively unaltered.