Physiological values of ECG parameters in Silesian horses

The aim of this study was to establish the physiological ECG values in the Silesian horse and to compare the results with literature data for other breeds of horses. This study was carried out on 31 healthy Silesian horses (15 males and 16 females) aged 2-19 years. The ECG was carried out after an anamnesis and clinical examination and without prior premedication or use of force, both of which could affect the ECG result. The mean heart rate (HR) in the Silesian horses was 39 +/- 8.1 beats per minute. In the majority of the leads, P waves were single positive waves. Notched waves were present in 16-51% of the horses, bifid waves were found less frequently, and biphasic P waves were seen least frequently. In the aVR lead, the P wave was most commonly found to be single negative. The PQ interval ranged from 0.18 s in the CV1 lead to 0.29 s in the aVR lead. Most often, the PQ interval lasted 0.24-0.28 s. The QRS duration ranged from 0.079 s in the CV1 lead to 0.099 s in lead III. The QRS duration was between 0.08 and 0.1 s. Generally, the T wave was single positive or negative. It was biphasic only in the precordial leads. Unlike P waves, notched T waves were not found. The ECG parameters in the Silesian horse do not differ from normal ECG values for other horse breeds of similar weight. Specific features of the ECG in the Silesian horse are a frequent occurrence of additional R' and S' waves in the Einthoven leads and a relatively long supraventricular conduction time.