Objective:To observe the effects of paw preferences on drug reaction to Pentobarbital sodium in mice.Methods:96 adult Kunming mice were separated into two groups(left-paw and right-paw)by skilled reaching test.Each group was treated with Pentobarbital sodium with sub-anesthetic dosages 20 mg/(kg·week)

anesthetic dosages 60 mg/(kg·week) and followed by LD50 test.Results:The ratio of left-paw and right-paw mice is 2 to 3

and there is no difference between two genders.Spontaneous activities of the left-paw mice are significantly lower than those of the right-paw with sub-anesthetic dosages.Sleeping duration of the left-paw is markedly shorter than the right-paw with anesthetic dosages.There is no difference in LD50 test of Pentobarbital sodium between the two groups.Conclusion:The paw preference may affect physiological reaction to drugs in mice.The deeper study on this phenomenon may provide the basis of clinically personalized medicine.