This study was designed to demonstrate the effects of surgical skills of final-year veterinary medicine students relating to total surgery time and skin incision length on postoperative stress, oxidative stress and pain in bitches undergoing ovariohysterectomy under identical anaesthesia and surgical procedures. The control group (n=12) consisted of bitches that were operated on by an experienced surgeon, while the ovariohysterectomies in the experiment group (n=12) were performed by final-year veterinary medicine students. Blood samples were taken 24 hours before the surgery, during premedication, at the end of surgery and 30 minutes, 1, 2, 4 and 6 hours after surgery for the analysis of cortisol, total oxidant status (TOS), total antioxidant status (TAS) and for the calculation of the oxidative stress index (OSI). Modified Melbourne Pain Scale was used for pain assessment. It was observed that the total surgery time and length of skin incision in the experiment group were significantly higher (p<0.001) than those detected in the control group. The concentrations of cortisol were statistically higher (p<0.001) in the experiment group than those measured in the control group, apart from the concentrations measured at 24 hours before surgery. The concentrations of TOS and TAS did not show any significant differences within and between groups. Similarly, OSI did not differ within groups. However, OSI values at premedication time in the experiment group were statistically higher (p<0.05) than those calculated in the control group. Pain scores did not differ within and between groups. In conclusion, it is indicated that the blood cortisol concentrations tend to increase due to the surgery time or the length of skin incision. Moreover, ovariohysterectomies may be safely performed by final-year veterinary medicine students without any postoperative pain.