Comparative evaluation of the sedative and physiological effects of medetomidine alone and in combination with pethidine, morphine, tramadol, and methadone in goats

Background The use of combinations of α2‐adrenergic agonists and opioids has been published as providing superior sedation than either drug alone. Introduction The present study aims to compare the sedative and physiological effects of intravenous (IV) administration of medetomidine alone and in combination with methadone, morphine, tramadol, and pethidine in goats. Methods Ten healthy goats aged 12 ± 3 months and weight of 22 ± 4 kg were used in an experimental, crossover (Latin square), randomized, and blinded study. The animals were assigned to five IV treatments with a minimum washout period of 8 days between treatments: medetomidine (20 μg kg−1), medetomidine/methadone (0.5 mg kg−1), medetomidine/morphine (0.5 mg kg−1), medetomidine/tramadol (5 mg kg−1), and medetomidine/pethidine (1 mg kg−1). Results Clinical adverse effects such as tremors (facial and generalized), bruxism, nystagmus, mydriasis, and vocalization were presented in all the medetomidine/opioid treatments. Clinical adverse effects were observed at 10–90 minutes in medetomidine/opioid treatments. Animals in all treatments were sedated at 5–90 minutes. Sedation was significantly higher in medetomidine/opioid treatments than in medetomidine at 15–30 minutes after administration (P