Effects of midazolam or midazolam-fentanyl on sedation and analgesia produced by intramuscular dexmedetomidine in dogs

Abstract

The study was conducted to evaluate and compare sedation, analgesia and muscle relaxation, and other systemic changes produced by dexmedetomidine, dexmedetomidine-midazolam and dexmedetomidine-midazolam-fentanyl in 12 apparently healthy adult dogs divided into three groups (n - 4). In a prospective randomised blinded study, the dogs received 20 μg kg -1 dexmedetomidine (group A), 20 μg kg -1 dexmedetomidine and 0.2 mg kg -1 midazolam (group B), and 20 μg kg -1 dexmedetomidine, 0.2 mg kg -1 midazolam and 4 μg kg -1 fentanyl (group C), through intramuscular route. All the drugs were given simultaneously using separate syringes. Dexmedetomidine produced moderate sedation and muscle relaxation and mild to moderate analgesia with mild depression of laryngeal reflex. Addition of midazolam resulted in excellent muscle relaxation, deep sedation and moderate analgesia with moderate depression of laryngeal reflex. Weak time and down time were decreased whereas time to return of righting reflex and recovery time were increased. Heart rate, respiratory rate and rectal temperature and pulse oximeter values did not differ significantly between groups A and B. Addition of fentanyl further accentuated muscle relaxation, analgesia and produced deep sedation and allowed easy intubation without any further depression of clinical parameters. It reduced the onset time and increased recovery time further. It was concluded that addition of midazolam enhances the sedation and muscle relaxation produced by dexmedetomidine. The combination of fentanyl-dexmedetomidine-midazolam results in excellent analgesia, sedation and muscle relaxation with favourable conditions for intubation which may be used to perform diagnostic or minor surgical operations in dog. © 2011 Knowledgia Review, Malaysia.