Atrial FibrillationArrhythmiaConduction DisordersCanine

AF/DCM Dobie

Case of Atrial Fibrillation and DCM in a 4-year old hound named Dobie. Dobie used to be happy puppy

November 4, 2025
6 min read
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AF/DCM Dobie
Patient: 5 year old Doberman Pinscher

Presentation: Acute exercise intolerance and coughing

Exam: Rapid, irregular rhythm; possible left ventricular enlargement or CHF

ECG Findings

Left Axis Deviation Angle seen here
Normal Sinus Rhythm 12 Lead ECG

Pathophysiology of Atrial Fibrillation

Key Concepts
  • AF requires a critical mass of atrial tissue for reentry circuits to sustain the rhythm
  • Common in medium- to large-breed dogs (e.g., Dobermans, great danes) with atrial enlargement secondary to DCM
  • Loss of coordinated atrial contraction → ↓ ventricular filling (loss of atrial “kick”) → ↓ cardiac output.
  • Rapid ventricular rates further reduce stroke volume and worsen heart failure symptoms.

Clinical Correlation

  • AF: Strong association with dilated cardiomyopathy (DCM)
  • Clinical signs: coughing, weakness, exercise intolerance, collapse.
  • Physical findings: pulse deficits, variable pulse quality, systolic murmur, and signs of low cardiac output

Diagnostic Workup

Next Steps
  • Thoracic radiographs: Evaluate pulmonary congestion & cardiomegaly
  • Echocardiography: Confirm DCM (dilated LV, reduced fractional shortening)
  • Blood pressure & biomarkers (NT-proBNP, troponin I)
  • Holter monitoring: Assess rate control efficacy & rhythm burden

Testing Text