Three-lead ECG in a golden retriever with dilated cardiomyopathy. Atrial fibrillation in this dog is being treated with digoxin and diltiazem. P waves are still not discernible and the rate is still irregular but at a much slower ventricular response rate because of blockade of the AV node. The average heart rate is now 100140 bpm (paper speed, 50 mm/sec; sensitivity, 10 mm/mV).
