Acepromazine-dexmedetomidine-ketamine for injectable anaesthesia in captive European brown hares (Lepus europaeus)

Objective To evaluate a combination of acepromazine, dexmedetomidine and ketamine (ADK) on induction and recovery from anaesthesia, and on physiological parameters in hares undergoing non-invasive procedures. Study design Prospective clinical study. Animals Sixteen European hares (Lepus europaeus), seven males and nine females, aged (mean +/- SD) 3.25 +/- 0.9 months and weight 2.1 +/- 0.6 kg. Methods Acepromazine 1% (A), dexmedetomidine 0.05% (D) and ketamine 5% (K) were mixed and given intramuscularly (IM) at 0.25 mL kg(-1), representing 10 mg kg(-1) K, 0.25 mg kg(-1) A, 12.5 mu g kg(-1) D. If the righting reflex was present after four minutes, a second injection of 0.15 mL kg(-1) (6 mg kg(-1) K, 0.15 mg kg(-1) A, 7.5 mu g kg(-1) D) was administered IM. Surgical anaesthesia was judged as present when righting, palpebral, ear-pinch and pedal withdrawal reflexes were absent. Anaesthetized hares were tagged, and underwent blood sampling and ocular ultrasound examination. Physiological parameters were recorded every ten minutes, and were compared by Kruskal-Wallis tests. Results A single dose induced loss of righting reflex in 11/16 (69%) hares within four minutes; the second dose was effective in the remaining hares. Ten minutes after the loss of the righting reflex, a surgical plane of anaesthesia was present in all hares. Sleep time to regaining righting reflex was 34 +/- 11 (range 21-62) minutes and recovery was calm. Although there were some statistical differences over time, cardiovascular parameters remained within an acceptable range but there was respiratory depression and hares were hypoxemic. Conclusions and clinical relevance The ADK mixture produced a smooth and rapid induction of anaesthesia, a low incidence of untoward side effects and full recovery after four hours. Supplementary oxygen might be advisable if a deeper plane of anaesthesia was required. Chemical restraint was adequate to perform non-invasive procedures.