Evaluation of a new smartphone-based stethoscope with one‑lead electrocardiogram in healthy sheep

Diagnostic tests commonly used for assessing of cardiac diseases in clinical practice are not always available in small ruminants, therefore cardiac auscultation is a cornerstone in this species. The present study assesses the reliability of a new smartphone-based digital stethoscope featuring simultaneous phonocardiography and one-lead electrocardiogram to evaluate heart sounds and electrocardiographic (ECG) findings in healthy sheep. Additionally, we compared the effect of breed (Bergamasca vs Comisana breed) on the ECG tracings obtained by the digital stethoscope. A total of 44 sheep (23 Bergamasca and 21 Comisana sheep) were recruited. No sheep ausculted abnormally with either the conventional or digital stethoscope. All audio recordings were considered interpretable in 40 sheep with substantial agreement (k = 0.755) between two operators. Conventional and digital ECG tracings showed sinus rhythm in all sheep and the limit of agreement analysis showed similar values between the two devices, but some ECG variables were not interchangeable. A perfect-to-good agreement was observed for heart rate, P wave duration/amplitude, PQ interval, QRS duration and QT interval; substantial difference for the S wave amplitude and moderate agreement (k = 0.569) for the T wave morphology between the two devices were observed. A fair agreement was found for the artifact presence (k = 0.395). Comparison of ECG variables between "Bergamasca" and "Comisana" breed showed differences (p < 0.05) for heart rate, QRS duration, QT duration and T polarity. In conclusion, the digital stethoscope Eko DUO is a practical and easy-to-use tool for assessing heart sounds and ECG signals in sheep in the field.