Clinical judgment required. This calculator is a decision-support tool, not a substitute for veterinary consultation.

Mean Electrical Axis CalculatorCanineFeline

Calculate the mean electrical axis (MEA) of the heart from ECG leads I and III in dogs and cats. Uses the net QRS amplitude (sum of all positive and negative deflections) from bipolar limb leads I and III to determine the cardiac axis in degrees via trigonometric calculation. Normal canine MEA ranges from +40° to +100°; normal feline MEA ranges from 0° to +160°. Interprets results as normal axis, left axis deviation (LAD), or right axis deviation (RAD). Used for ECG interpretation, cardiac arrhythmia assessment, bundle branch block identification, ventricular hypertrophy evaluation, and electrophysiology workup. Common queries: 'mean electrical axis dog ECG', 'cardiac axis calculation', 'left axis deviation dog', 'ECG axis interpretation veterinary'.

Species

Lead I Net QRS Amplitude

Lead III Net QRS Amplitude

Mean Electrical Axis

—°

Interpretation

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100

Moderate

Low

Moderate