MALIGNANT VENTRICULAR DYSRHYTHMIA IN BROILER-CHICKENS DYING OF SUDDEN-DEATH SYNDROME

A flock of broiler chickens was monitored intensively for overt signs indicative of sudden death, Electrocardiographic tracing of terminal c ardiac activity was obtained from six broilers succumbing to sudden de ath syndrome and from six control chickens which were killed by cervic al dislocation, Normal sinus rhythm, heart rate and electrocardiogram (EGG) pattern with P, QRS, and T deflections were observed for two to three minutes in the control chickens, The ECG tracing from birds dyin g of sudden death syndrome showed no identifiable P, QRS, or T wavefor ms, Initial more regular oscillatory waves resembling ventricular flut ter, changed to irregular, undulating waves characteristic of ventricu lar fibrillation. A straight line, indicating cessation of heart activ ity, appeared within four to six minutes of the onset of clinical sign s. It was concluded that the sudden death syndrome is associated with an acute cardiovascular failure caused by a lethal cardiac dysrhythmia , ventricular fibrillation.