Behavioral and cardiopulmonary effects of dexmedetomidine-midazolam and dexmedetomidine-midazolam-butorphanol in the silver fox (Vulpes vulpes).

OBJECTIVE: To evaluate the behavior and some cardiopulmonary variables of dexmedetomidine-midazolam or dexmedetomidine-midazolam-butor-phanol in the silver fox (Vulpes vulpes). STUDY DESIGN: Blinded, randomized design. ANIMALS: Sixteen adult silver foxes, aged 7-9 months, weighting 6.0-9.2 kg. METHODS: Animals were randomly assigned to dexmedetomidine (50 µg kg-1) and midazolam (0.45 mg kg-1) (group DM) or to dexmedetomidine (30 µg kg-1), midazolam (0.45 mg kg-1) and butorphanol (0.25 mg kg-1) (group DMB), administered intramuscularly. Pulse rate (PR), respiratory rate (fR), noninvasive arterial pressures, oxygen saturation (SpO2), rectal temperature (T) and behavioral scores (posture, sedation, antinociception, jaw relaxation and auditory response) were measured at 5, 10, 20, 30, 40, 50 and 60 minutes after injection. Time from drug injection to recumbency with no response to stimuli (IT) and time from administration of atipamezole (0.2 mg kg-1) to standing with coordination (RT) were recorded. The occurrences of adverse events were recorded. Data were analyzed by two-tailed unpaired t-tests and Bonferroni post hoc tests. Significant differences were accepted at p<0.05. RESULTS: There were no statistically significant differences between the groups for IT or RT. Arterial pressures were higher in DMB at each time point except at 5 minutes. PR was lower in DM at each time point except at 10 and 60 minutes. No significant difference was found between the groups for fR, SpO2 and T. The behavioral scores were significantly lower (lower quality immobilization) in DMB at 5,10 and 60 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: IT and RT were not different between the groups. Both protocols provided immobilization for 30-40 minutes with excellent muscle relaxation and analgesia adequate for clinical examinations and some simple surgical procedures.

Comparison of the effects of propofol and emulsified isoflurane alone or combined with dexmedetomidine on induction of anesthesia in dogs.

OBJECTIVE: To compare the respective effects of propofol and emulsified isoflurane administered alone and in combination with dexmedetomidine on the quality of induction of anesthesia, physiological variables and recovery in dogs. STUDY DESIGN: Prospective, randomized, experimental trial. ANIMALS: Thirty-six adult mixed-breed dogs. METHODS: Animals were randomly assigned to one of four induction protocols: propofol alone (group P); emulsified isoflurane alone (group EI); both propofol and dexmedetomidine (group PD), or both emulsified isoflurane and dexmedetomidine (group EID). Pulse rate (PR), respiratory rate (fR ), non-invasive arterial blood pressure and arterial blood gases were measured at baseline, before induction, immediately after intubation (time 0), and at 5 minute intervals until the dog began to swallow and the trachea was extubated. The quality of induction and recovery, and degree of ataxia were scored by a single investigator unaware of group assignment. The durations of anesthesia and recovery, and the incidence of adverse events were recorded. RESULTS: There were no clinically significant differences among the groups in induction quality. Systolic arterial pressure was lower in EID compared with P at 5 minutes. PR and fR were lower in PD and EID compared with P after induction. The PaCO2 at 5 minutes was higher than at baseline in group P. Ataxia score was lower in EID than in P. Time from induction to extubation and time from extubation to sternal recumbency were lower in EID compared with PD. CONCLUSIONS AND CLINICAL RELEVANCE: There were no clinically significant differences among the groups in induction quality. In PD and EID, but not in P, PR and fR were decreased after induction. The EID combination resulted in smooth and rapid induction and recovery and thus may be useful clinically for induction of anesthesia.