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

Consequences:

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

Treatment:

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