Tidal breathing flow-volume loop analysis as a test of pulmonary function in exercising horses

Area of Science:

• Equine respiratory medicine
• Pulmonary function testing
• Cardiopulmonary exercise physiology

Background:

• Tidal breathing flow-volume loops (TBFVL) are used to assess pulmonary function.
• Evaluating TBFVL in exercising horses with induced lung disease is important for diagnostic accuracy.
• Obstructive lung disease in horses can significantly impact respiratory function.

Purpose of the Study:

• To investigate the utility of TBFVL in detecting pulmonary function changes in Standardbreds with induced obstructive lung disease during treadmill exercise.
• To compare TBFVL indices in horses with and without airway obstruction at varying exercise intensities.

Main Methods:

• Six Standardbred horses were used in the study.
• Allergic lung disease was induced using ovalbumin.
• Pulmonary function was assessed using TBFVL at rest and during treadmill exercise (75% and 100% maximum heart rate) before and after disease induction.
• Pulmonary resistance was measured to characterize the obstructive lung disease.

Main Results:

• Horses with induced allergic lung disease exhibited moderate obstructive lung disease at rest, indicated by increased pulmonary resistance.
• Quantitative indices derived from TBFVL (shape and size) showed no significant differences between horses with airway obstruction and clinically normal horses during exercise at 75% and 100% maximum heart rate.

Conclusions:

• TBFVL may not be a sensitive tool for diagnosing airway obstruction in exercising horses, even when moderate obstructive lung disease is present.
• Further research into more sensitive pulmonary function tests for exercising horses with respiratory conditions is warranted.