Medetomidine/midazolam/ketamine anaesthesia in ferrets: effects on cardiorespiratory parameters and evaluation of plasma drug concentrations.

ABSTRACT

OBJECTIVE: To evaluate the cardiorespiratory effects and plasma concentrations of medetomidine-midazolam-ketamine (MMK) combinations administered by intramuscular (IM) or subcutaneous (SC) injection in sable ferrets (Mustela putorius furo). STUDY DESIGN: Prospective randomized experimental study. ANIMALS Eighteen adult ferrets weight median 1.19 (range 0.81-1.60) kg. METHODS: Animals were allocated to one of three groups group IM07 received 20 µg kg(-1) medetomidine, 0.5 mg kg(-1) midazolam and 7 mg kg(-1) ketamine IM; group IM10 20 µg kg(-1) medetomidine, 0.5 mg kg(-1) midazolam and 10 mg kg(-1) ketamine IM; and group SC10 20 µg kg(-1) medetomidine, 0.5 mg kg(-1) midazolam and 10 mg kg(-1) ketamine SC. Following instrumentation, cardiorespiratory parameters and plasma drug concentrations were measured every 5 minutes (T5-T30) for 30 minutes Ferrets were then euthanased. Data were analysed using anova for repeated measures. p<0.05 was considered significant. RESULTS: Results are mean ± SD. Induction of anaesthesia (minutes) in IM07 and IM10 [2 (1)] was significantly faster than in SC10 [5 (2)]. All groups demonstrated the following results given as groups IM07, IM10 and SC10 respectively. Mean arterial blood pressures (mmHg) were initially high [186 (13); 174 (33) and 174 (9) at T5] but decreased steadily. Pulse rates were initially 202 (20), 213 (17) and 207 (33) beats minute(-1) , decreasing with time. PaO(2) (mmHg) was low [54.0 (8), 47.7 (10) and 38.5 (1)] at T5, although in groups IM07 and IM10 it increased over time. Plasma concentrations of all drugs were highest at T5 (36, 794 and 8264 nmol L(-1) for medetomidine, midazolam and ketamine, respectively) and decreased thereafter for both midazolam and ketamine, concentrations in IM07 and IM10 were higher than SC10. CONCLUSIONS AND CLINICAL RELEVANCE MMK combinations containing either 7 or 10 mg kg(-1) ketamine and given IM are suitable combinations for anaesthetising ferrets, although the observed degree of hypoxaemia indicates that oxygen administration is vital.