Breath characteristics and adventitious lung sounds in healthy and asthmatic horses

Thoracic auscultation is central in the diagnostic work-up of horses suffering from respiratory disorders. However, it suffers from limitations, including low sensitivity for transient or localized lung sounds, subjectivity, and lack of systematic analysis. In this study, we introduced a digital stethoscope designed to autonomously record lung sounds over prolonged periods, in multiple locations simultaneously. Breath parameters and occurrence of adventitious sounds were compared between 12 healthy horses and 22 horses with asthma (12 mild to moderate, 5 severe in remission, and 5 severe in exacerbation). Each horse was digitally auscultated in 11 locations simultaneously for 1 hour. One hundred breaths per recording were randomly selected, blindly categorized, and statistically analyzed. Digital auscultation provided high-quality recordings. Compared to clinically healthy controls, all adventitious sounds were significantly more frequent and breath intensity significantly higher in severely asthmatic horses in exacerbation, but not in those in remission and in mild to moderately affected horses. This digital approach overcomes traditional auscultation limitations, offering potentially more accurate assessments of equine respiratory conditions for diagnosis and monitoring. However, larger, well-characterized samples are needed to distinguish mild to moderate asthmatic horses from healthy ones.