need help concerning anaesthesia in in vivo experiment

[Didier Morin]

I worry about my in vivo experiments on the rabbit. The anaesthesia that I use
(pentobarbital) induces an inhibition of locomotor activities during 6 hours. 
However,  the time surgery lasts up to 4 hours. Then, I need to reduce the time
effect of the anaesthesia. Could anyone know an other anaesthetic (except 
halothane, fluothane or any that kind of anaesthetics) able to satisfy my 
experimental conditions?
Thank you in advance,

Agnes Bonnot

E-mail : morin at neuromotri.u-bordeaux.fr