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The definitive diagnosis of canine DCM is by echocardiography with the demonstration of ventricular dilation and reduced contractility (systolic dysfunction).

In the absence of echocardiography, usually presumptive evidence of canine DCM can be obtained:

a) Radiology:

  • Pulmonary venous congestion/pulmonary edema in cases of CHF
  • Left ventricular enlargement
  • Left atrial enlargement
  • Pleural effusion – noted in 21% of dogs at the time of presentation for CHF (Bronsoiler J Thesis 2005)

Peritoneal effusion in cases of right heart failureHepatomegaly

b) Electrocardiography: may reveal:

  • May be normal
  • Infrequent to frequent ventricular arrhythmias
    • VPCs were observed in 84% of giant breed dogs, 76% of large breed dogs, 58% of Spaniels, and 82% of Dobermans at the time of presentation for CHF (Bronsoiler J Thesis 2005).
  • Supraventricular premature beats, especially atrial fibrillation
    • Atrial fibrillation was observed in 76% of giant breed dogs, 35% of large breed dogs, 11% of Spaniels, and 38% of Dobermans with CHF (Bronsoiler J Thesis 2005).
  • Left ventricle enlargement
  • Left atrial enlargement
  • ST segment depression
  • Wide QRS duration
  • Microscopic intramural myocardial infarction (MIMI) (notch in the QRS complex)

Note: none of these findings are diagnostic of canine DCM

c) Blood Work:

  • Evidence of reduced cardiac output as per Bloodwork in Clinical Evaluation of Heart Disease
  • A deficiency in plasma taurine may occur in Cocker Spaniels and other dogs
  • A deficiency in plasma carnitine may occur in giant breed dogs and boxers
  • Elevated cardiac Tn-I

Elevated NT-proBNP (see proBNP in the Clinical Evaluation of Heart Disease section)