Evaluation of the sedative and physiological effects of xylazine, detomidine, medetomidine and dexmedetomidine in goats

Abstract

Background: Many α₂ -agonists are commonly used for sedation and analgesia in ruminants.

Introduction: The present study aims to compare the sedative and physiological effects of intravenous (IV) administration of xylazine, detomidine, medetomidine and dexmedetomidine in goats.

Methods: Ten healthy goats aged 6 ± 1 months and weighing 15 ± 2 kg were used in experimental, crossover Latin square, randomised and blinded study. Animals were assigned to five IV treatments: control (normal saline); xylazine (100 μg kg^-1 ); detomidine (50 μg kg^-1 ); medetomidine (20 μg kg^-1 ) and dexmedetomidine (5 μg kg^-1 ). The degree of sedation was investigated using a numerical ranking scale of 0-10. Sedation scores were compared at each time using nonparametric (Kruskal-Wallis and Mann-Whitney U) tests.

Results: Heart rate (HR), respiratory rate (RR), rectal temperature (RT), ruminal motility and capillary refill time (CRT) were performed before (baseline) and after drug administration. Animals in α₂ -adrenergic agonist treatments were sedated at 5-60 min. There were no significant differences among α₂ -adrenergic agonist treatments at 5-60 min in sedation scores. HR significantly decreased from baseline 5-90 min after α₂ -adrenergic agonists' administration. Ruminal motility was decreased in α₂ -adrenergic agonist treatments at 5, 90 and 120 min and absent at 10-60 min. A significant decrease from baseline in RR was detected between 30 and 90 min after α₂ -adrenergic agonists' administration. RT was unchanged in any treatment for 120 min. CRT was less than 2 s at all time points following each treatment.

Conclusions: The duration of sedation was up to 60 min after IV administration of xylazine (100 μg kg^-1 ), detomidine (50 μg kg^-1 ), medetomidine (20 μg kg^-1 ) and dexmedetomidine (5 μg kg^-1 ) in goats in this study. No significant differences were detected between xylazine, detomidine, medetomidine and dexmedetomidine in goats.

Keywords: goats; physiological variables; sedative effects; α2-adrenergic agonists.