Lesson 11 of 14
In Progress

Low Amplitude QRS Complex

ECG Findings:

  1. Total excursion of the QRS complex is reduced
    • <20 kg dog: <1 mV
    • >20 kg dog: <1.5 mV
  2. Other rhythm disorders may be present

Etiologies may include:

  1. Pleural effusion
  2. Pericardial effusion
  3. Obesity
  4. Hypothyroidism
  5. Pneumothorax
  6. Diffuse myocardial disease
  7. Normal variation


  • There is no hemodynamic significance associated with low amplitude QRS complexes. The underlying problem may have significant hemodynamic impact, however.


  • None required for the ECG finding
  • The underlying disorder should be sought out and treated, if needed