Comparison of two immobilisation protocols (medetomidine-midazolam and alfaxalone-midazolam) for restraint of urban red foxes (Vulpes vulpes) : a pilot study.

OBJECTIVE

To compare two immobilisation protocols for the restraint of urban red foxes: medetomidine-midazolam (MM) and alfaxalone-midazolam (AM).

STUDY

DESIGN

Prospective, randomised clinical trial.

ANIMALS: Fourteen urban red foxes (Vulpes vulpes) captured in the Dublin metropolitan area.

METHODS

Foxes were randomly assigned to receive either MM [medetomidine 0.07 mg kg-1, midazolam 0.8 mg kg-1 intramuscularly (IM)] or AM (alfaxalone 3 mg kg-1, midazolam 0.8 mg kg-1 IM). Sedation and recovery were scored. Recovery times and physiological variables [heart rate, respiratory rate (fR), oscillometric arterial blood pressure, arterial haemoglobin oxygen saturation (SpO2) and rectal temperature] were measured. Hair and blood samples were collected for cortisol analysis. Sedation was reversed with atipamezole (0.35 mg kg-1 IM) and/or flumazenil (0.01 mg kg-1 IM). Recovery ended when foxes walked with coordinated movements. Data were analysed using linear and mixed-effects models.

RESULTS

Seven foxes were given MM and seven AM. Median sedation scores were higher in MM (14.5 versus 12.5; p = 0.048), with shorter reversal times (25 versus 54 minutes; p = 0.009). Heart rate was lower (80 versus 216 beats per minute-1; p < 0.001) and mean arterial blood pressure higher (147 versus 110 mmHg; p < 0.001) in MM. SpO2 was higher in AM (95 versus 91%; p = 0.015). Rectal temperature was higher in MM (38.6 versus 36.5 °C; p < 0.001), with a faster decrease in AM (p = 0.006). fR did not differ between groups (p = 0.492) but increased with higher ambient temperature (p = 0.04) and decreased with higher hair cortisol levels (p = 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE: Both protocols provided sufficient sedation for intended procedures. MM resulted in higher sedation scores and faster recovery after antagonist administration, while AM provided higher SpO2 and heart rates and lower rectal temperature values.