Effect of body position on electrocardiographic parameters in Labrador retriever dogs

Abstract

Objective: This study aimed to determine how body position influenced values of electrocardiographic (ECG) parameters in Labrador retriever dogs.

Materials and Methods: ECGs were recorded from 10 Labrador retriever dogs in 3 positions, right lateral (RL) recumbence, standing (ST) position, and left lateral (LL) recumbence). The standard bipolar limb leads (leads I, II, and III) and unipolar augmented limb leads (leads aVR, aVL, and aVF) were recorded. Amplitude and durations of P, QRS, and T wave, PR and QT intervals, mean electrical axis (MEA), and heart rate (HR) were measured from each recording. Results: No significant difference was observed in P wave duration (P=0.69), P wave amplitude (P=0.88), PR interval (P=0.85), QRS duration (P=0.18), R wave amplitude (P=0.24), and HR (P=0.42) among the 3 positions. The values of T wave duration, T wave amplitude and QT interval were significantly decreased in ST position compare to RL recumbency (P=0.03, 0.01, and 0.02, respectively). The value of MEA was not significantly different in LL recumbence compared to RL recumbence. However, MEA was significantly decreased in the ST position compare to RL recumbency (P<.0001).

Conclusion: Our findings indicated that the mean electrical axis shift to leftward and with increasing incidence of a muscle tremor artifact in ECG recording with Labrador retriever dogs in standing position. It is necessary to assess ECG from a large number of dogs to establish reference values in other position. However, when investigators require accurate ECG measurement and interpretation of the amplitudes and MEA, recording with the dog in right lateral recumbence is recommended.