Effect of body position on electrocardiographic recordings in dogs

OBJECTIVE: To determine whether body position (standing vs right lateral recumbency) altered the quality of the electrocardiogram (ECG) and value of ECG variables in dogs when the ECG was recorded using American Heart Association guidelines for frequency response. DESIGN: Crossover study using a convenience sample. METHODS: ECGs were recorded twice in 65 sled dogs in random order with each dog standing or placed in right lateral recumbency. Lead II and three semi-orthogonal leads (I, aVF, and V10 ) were recorded and muscle tremor artefact was assessed. RESULTS: Lead II ECGs obtained from dogs in right lateral recumbency had less muscle tremor artefact and consequently a shorter QRS duration than ECGs obtained with the dogs standing. The P, Q, R and S wave amplitudes differed in selected leads and the mean electrical axis was shifted 20° to the right when dogs were in right lateral recumbency. CONCLUSIONS: Right lateral recumbency improves the quality of ECG recording in dogs by decreasing muscle tremor artefact, alters the amplitude of P, R and S waves in specific leads and results in a rightward shift in the mean electrical axis, relative to standing.