Differences in pulmonary function measured by oscillometry between horses with mild-moderate equine asthma and...

Area of Science:

• Veterinary Medicine
• Pulmonary Physiology
• Equine Health

Background:

• Mild-moderate equine asthma (MEA) diagnosis relies on endoscopy, bronchoalveolar lavage fluid (BALf) cytology, and indirect pleural pressure measurement.
• Oscillometry is a non-invasive pulmonary function test with potential for MEA diagnosis, but its efficacy in detecting subclinical airway obstruction requires further evaluation.

Purpose of the Study:

• To compare lung function parameters obtained via oscillometry in healthy horses versus those with MEA.
• To determine if oscillometry can differentiate between healthy and MEA-affected equine subjects.

Main Methods:

• A prospective case-control study involving 37 horses, categorized as healthy or MEA-affected based on clinical signs and diagnostic procedures.
• Oscillometry was performed on all horses across a frequency range of 2-6 Hz, analyzing resistance (Rrs) and reactance (Xrs) parameters.
• Statistical analysis included repeated-measures two-way ANOVA, t-tests, and receiver operating characteristic (ROC) curve analysis to identify diagnostic cut-off values.

Main Results:

• No significant differences in overall resistance (Rrs) or reactance (Xrs) were found between healthy and MEA groups.
• A significant difference in the frequency dependence of whole-breath and inspiratory reactance (Xrs) was observed between the two groups (p < 0.05 and p < 0.01, respectively).
• The frequency dependence of inspiratory Xrs identified a cut-off value of -0.06 cmH2O/L/s with 86.4% sensitivity and 66.7% specificity for MEA diagnosis.

Conclusions:

• Oscillometry, particularly the analysis of reactance (Xrs) frequency dependence, shows promise as a non-invasive diagnostic tool for mild-moderate equine asthma (MEA).
• Further research with larger sample sizes and comprehensive diagnostic criteria for control groups is warranted.