Anaesthetic effects in the ferret of alfaxalone alone and in combination with medetomidine or tramadol: a pilot study

Alfaxalone is a neurosteroid with anaesthetic effects and it has been used successfully in several animal species. However, there are no data, to our knowledge, about its efficacy and safety in ferrets (Mustela putorius furo). We evaluated a variety of anaesthetic regimens in ferrets, namely, alfaxalone at 20, 10 and 5mg/kg (n=1, 10 and 9, respectively; intravenously); medetomidine at 20 mu g/kg (n=3; intramuscularly); medetomidine (20 mu g/kg, intramuscularly) plus alfaxalone (2.5mg/kg, intravenously; n=7); and tramadol (5mg/kg, intramuscularly) plus alfaxalone (5mg/kg, intravenously; n=2). Two animals treated with alfaxalone at 10mg/kg and 20mg/kg, respectively, died. At 5mg/kg alfaxalone produced anaesthesia with a similar onset but a shorter duration of anaesthesia and analgesia than alfaxalone at 10mg/kg. The medetomidine-alfaxalone combination produced anaesthesia and analgesia of a longer duration than alfaxalone administered alone at 5mg/kg (P<0.0001 and P<0.001, respectively). Under this anaesthetic regimen, there was a progressive decrease in pulse rate during the first 30min before the pulse rate stabilized. Respiratory parameters were maintained at acceptable levels. When tramadol was administered, all the animals exhibited a strong excitation reaction and in no case was the toe-pinch reflex clearly abolished. Thus, alfaxalone plus medetomidine provided safe and effective anaesthesia in ferrets. Alfaxalone, alone or in combination with tramadol, did not produce satisfactory results for use as an anaesthetic for this species.