Measurement of respiratory function by impulse oscillometry in horses

Area of Science:

• Equine respiratory physiology
• Pulmonary function testing
• Forced oscillation technique

Background:

• Traditional pulmonary function tests have limited clinical use due to technical challenges and low sensitivity.
• Impulse oscillometry (IOS) presents a viable alternative for assessing respiratory function.

Purpose of the Study:

• To establish the feasibility, methodology, and repeatability of IOS in horses.
• To define reference values for respiratory resistance (Rrs) and reactance (Xrs) using IOS.
• To investigate the influence of biometrical parameters and compare IOS in healthy vs. heaves-affected horses.

Main Methods:

• IOS was performed on 38 healthy horses to establish reference values for Rrs and Xrs.
• Methodology focused on ensuring facemask airtightness, minimal dead space, and standardized head positioning.
• IOS measurements were compared between 6 healthy horses and 6 horses with clinical signs of heaves.

Main Results:

• Airtight facemasks and standardized head position were crucial for accurate IOS measurements.
• IOS measurements demonstrated repeatability in both healthy and diseased horses.
• Specific IOS parameters (increased R5Hz, R5Hz>R10Hz, and negative Xrs) indicated heaves crisis in affected horses.

Conclusions:

• Impulse oscillometry is a quick, minimally invasive, and informative pulmonary function test for horses.
• IOS shows promise for routine and field-based respiratory clinical assessments in equine practice.