The current study was conducted to find out the prevalence of cardiac arrhythmias in clinically healthy Iranian fat-tailed sheep in two physiological states, i.e., late pregnancy and early post-partum periods. The electrocardiogram (ECG) was recorded from 32 sheep (early post-partum, n=17 and late pregnant, n=15) without any clinical signs of cardiac diseases. Assessment of ECG revealed that 84.3% of sheep had one or two kinds of cardiac arrhythmias. Two types of cardiac arrhythmias which detected in this study were sinus tachycardia and sinus arrhythmia. The proportion of different cardiac arrhythmias between early post-partum and late pregnant sheep, were significantly (P=0.003) different. Sinus tachycardia was the most frequent arrhythmia recorded in both groups. Since none of the sheep with cardiac arrhythmias exhibited any clinical signs of heart disease at the time of ECG recording, the arrhythmias seen in this study could be regarded as physiological ones.

Key words: Cardiac arrhythmia; Electrocardiogram; Iranian fat-tailed sheep; Physiological arrhythmia