Comparison of the effects of ketamine, ketamine-medetomidine, and ketamine-midazolam on physiologic parameters and anesthesia-induced stress in rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) macaques

Abstract

This study compared the cardiovascular, respiratory, anesthetic, and glucocorticoid effects of ketamine alone with ketamine-medetomidine and ketamine-midazolam in rhesus and cynomolgus macaques. Macaques were given either intramuscular ketamine (10 mg/kg), intramuscular ketamine-medetomidine (3 mg/kg; 0.15 mg/kg), or oral midazolam (1 mg/kg) followed by intramuscular ketamine (8 mg/kg). The addition of medetomidine, but not midazolam, provided muscle relaxation and abolishment of reflexes that was superior to ketamine alone. In addition, medetomidine did not cause clinically relevant effects on cardiovascular and respiratory parameters when compared with ketamine. These 3 protocols did not have significantly different effects on fecal glucocorticoid metabolites. These results suggest that medetomidine can be a valuable addition to ketamine for healthy patients, whereas oral midazolam at the tested dose does not provide additional benefits.

Figure 1.

Experimental groups for sedation protocols.

Figure 2.

Scoring system for parameters of anesthetic depth. In addition, animals received a score of 1 if they were too awake to the test to be performed.