Immobilization of red fox (Vulpes vulpes) with medetomidine-ketamine or medetomidine-midazolam and antagonism with atipamezole.

Thirty-two free-ranging red foxes (Vulpes vulpes) were immobilized with one of three combinations: medetomidine (0.076 +/- 0.017 mg/kg) and ketamine (2.1 +/- 0.5 mg/kg; MK, n = 16), medetomidine (0.057 +/- 0.008 mg/kg) and low-dose midazolam (0.6 +/- 0.1 mg/kg; MM-0.5, n = 10), or medetomidine (0.067 +/- 0.012 mg/kg) and high-dose midazolam (1.3 +/- 0.2 mg/kg; MM-1, n = 6) by i.m. injection. Induction and recovery times were recorded. Pulse, respiratory rate, body temperature, systolic and diastolic blood pressure, and oxygen saturation were measured. Anesthesia depth indicators were observed. There was a significant difference between the MM-0.5 and the MM-1 groups regarding induction time, 8.1 +/- 2.1 min and 5.0 +/- 1.7 min, respectively. The MK induction time was 6.9 +/- 2.5 min, which was not significantly different from the other two groups. All combinations provided effective immobilization for at least 20-25 min. During immobilization, there were significant differences regarding rectal temperature, which was higher in the MK group; and blood pressure, which was higher in the MM-1 group. After administration of atipamezole at 5 mg per 1 mg medetomidine given, there was a significant difference between the groups in recovery time; MK foxes were standing within 3.9 +/- 1.7 min, MM-0.5 foxes within 10.6 +/- 4.5 min, and MM-1 foxes within 10.2 +/- 3.4 min. None of the combinations caused rough or prolonged recoveries. Subjectively, the MM groups had smoother and less ataxic recoveries than the MK group. In conclusion, the authors recommend the use of medetomidine at 0.07 mg/kg in combination with midazolam at 0.8 mg/kg or ketamine at 2 mg/kg for the immobilization of free-ranging red foxes. During immobilization, monitoring of body temperature and oxygenation is recommended.