Comparative evaluation of electrocardiographic effects of different doses of medetomidine and xylazine in calf-camels (Camelus dromedarius)

Abstract

This experimental, prospective, randomised, and blinded study aimed to perform comparative evaluation of electrocardiographic (ECG) effects of different doses xylazine and medetomidine in dromedary calves after intravenous (IV) administration. A total of twenty five clinically and paraclinically healthy male dromedary calves aged 15±2 weeks and weighing 95±5.5 kg were assigned randomly to five different groups (four experimental and one control). Groups XL and XH received a low (0.2 mg kg-1) and high (0.4 mg kg-1) dose of xylazine hydrochloride and groups ML and MH received a low (10 µg kg-1) and high (20 µg kg-1) dose of medetomidine hydrochloride once, IV. Finally, the control group (C) received normal saline in the same manner. ECG indices were evaluated on post treatment 0, 5, 10, 15, 30, 60, 90, 120 min, and 24 h. There was no significant difference in heart rate (HR) in all experimental groups at T90. HR was significantly lower after high doses than after low doses of medetomidine and xylazine at T120. HR was significantly lower in XH than in other groups of study at T24. At T90 QRS amplitude in XH was statistically lower than in control and XL groups. Analysis of P wave duration revealed that in MH and XH it was significantly longer than in ML, XL and control at T5. Duration of P wave in control group was significantly shorter than in all experimental groups from T10 to T90. RR interval duration was significantly shorter at T5 and T10 in control group compared to experimental groups. At T120, RR interval duration in MH and XH was considerably longer than that in ML, XL, and control. Compared with control group, cardiac arrhythmia scores were significantly lower than in all experimental groups from T5 to T60. At T90 and T120 in MH and XH, cardiac arrhythmia scores were significantly higher than those of XL, ML, and control. According to our findings, using low dose of medetomidine (10 µg kg-1) and xylazine (0.2 mg kg-1) was suggested in comparison with high dose of medetomidine (20 µg kg-1) and xylazine (0.4 mg kg-1) in dromedary calves with cardiac diseases in the field.