To verify availability of skin conductance (SC) as an indicator for the sympathetic nervous system (SNS) activity in dogs, the changes in SC and blood levels of stress-related hormones induced by drugs were compared. SC and cortisol, adrenaline and noradrenaline levels were measured in 5 dogs on 4 occasions with or without drug-induced sedation at 7-day intervals (no treatment, intramuscular medetomidine 0.01 mg/kg, intramuscular acepromazine 0.1 mg/kg and intravenous fentanyl 0.02 mg/kg). The fentanyl treatment produced significantly higher levels of SC and plasma cortisol and adrenaline compared with the other 3 treatments. The plasma noradrenaline level also tended to be higher following the fentanyl treatment. These results indicate that SC may reflect changes in the SNS activities in dogs.