Comparative electrocardiographic studies, and differing effects of pentazocine on ECG, heart and respiratory rates in young sheep and goats.

The effects of pentazocine on electrocardiogram (ECG) heart and respiratory rates were studied in young sheep and goats as a prelude to its clinical use as an opioid analgesic in the two species. The ECG was monitored by standard bipolar leads that provided discernible electrocardiographic features only in Lead I. Electrocardiograms of lambs differ significantly from those of kids with respect to QRS complex, P-R interval and T wave. Higher basal heart rate in lambs is apparently due to shorter P-R interval and shorter interval between successive cardiac cycles (p<0.05). Pentazocine, 3mgkg(-1) i.m., appears safer for lambs than kids as it significantly decreased P-R interval, Q-T interval, cardiac cycle duration, interval between successive cardiac cycles, respiration rate, and increased heart rate in kids but not in lambs (p<0.05).