Abstract
Background: Electrocardiographic (ECG) examination in birds is considered an inexpensive and non-invasive diagnostic aid for the recognition of infectious and metabolic diseases. Contrary to other bird species, studies describing normal ECG patterns for the Mandarin ducks (Aix galericulata) are lacking.
Aim: The aim of this study was to describe and evaluate normal ECG patterns in Aix galericulata.
Methods: Ten clinically healthy Mandarin ducks of both sexes, aged between 1 and 2 years and with body weight between 0.8 and 1.2 kg were included. Electrocardiograms were performed in a quiet room with animals conscious and manually restrained. All electrocardiographic parameters were recorded using standard (I, II and III) and augmented (aVR, aVL, and aVF) limb leads. The paper speed was set at 50 mm/sec. The amplitude was 1 mV=20 mm. Morphological patterns of P, QRS and T deflections were evaluated in all limb leads. The amplitude and the duration of waves and, their intervals were determined in lead II. The mean electrical axis (MEA) in the frontal plane was calculated using the Bailey hexaxial system.
Results: In all birds examined a regular sinus rhythm was observed. P waves were mainly positive in I, II, III, and aVF. A negative P wave was identified in aVR, while in aVL a great variability was present. The QRS complex was mainly isoelectric in I lead, while it was negative with rS or QS morphology in leads II, III and aVF. A positive polarity of QRS was detected in aVL with R pattern, while it was negative or positive with QS or R morphology respectively in aVF. T waves were mostly positive in lead II, III and aVF and, isoelectric in I lead. An ST slurring and Ta wave were observed in 2/10 and 8/10 respectively. The mean heart rate was 246 ± 90 beats per minute and the mean electrical axis was -88.8 ± 9.57°.
Conclusion: The ECG tracings of Mandarin ducks show similarities and some differences with the other avian species. The electrocardiographic values provided here can be used to assist in the interpretation of ECGs in Aix galericulata.

Key words: Key words: ECG, electrocardiogram, avian, Mandarin ducks, Aix galericulata