This study was performed to compare propofol, thiopental, etomidate and diazepam plus ketamin as induction agents for the isoflurane anesthesia in dogs. Experimental groups were divided into low groups (thiopental group: thiopental 15 mg/kg IV, propofol group: propofol mg/kg IV, etomidate group: etomidate 1.5 mg/kg IV, DZP+KET group: diazepam 0.5 mg/kg + ketamine 5 mg/kg, IV) and each group was consisted of 4 dogs. Cardiorespiratory changes (heart rate, $SpO_2$, respiratory rate, End-tidal $CO_2$ and body temperature), blood serum chemistry values (alkaline phosphatase, alanine aminotransforase, and total protein), and recovery and walking time were measured. The end tidal carbon dioxide level was significantly increased in the thiopental group (P<0.05). Heart rate and respiratory rate higher in the DZP+KET groups. There was hypothermia in all groups and significant decrease in body temperature was showed in thiopental group (p<0.05). Mean arousal time and mean walking time were significantly longer in thiopental group (P<0.05). Cardiovascular stimulating effects were minimal in etomidate group. Etomidate provides uneventful and rapid recovery.