Abstract
BACKGROUND: As one of the most common surgeries performed in veterinary medicine, ovariohysterectomy (OHE) can induce oxidative stress in dogs. The antioxidant properties of melatonin have been confirmed in various studies. This study aimed to investigate the effects of melatonin administration on oxidative stress in dogs before and after OHE. In this study, 25 mature female intact dogs were selected and randomly divided into five equal groups: Melatonin (melatonin, no surgery), OHE (no melatonin, surgery), OHE + melatonin (melatonin, surgery), anesthesia+melatonin (melatonin, sham surgery), and control (no melatonin, no surgery) groups. Melatonin (0.3 mg/Kg/day, p.o.) was administrated to the dogs in the melatonin, OHE + melatonin, and anesthesia+melatonin groups on days - 1, 0, 1, 2, and 3 (day 0 = OHE). Blood sampling was performed on days - 1, 1, 3, and 5 of the study. Blood samples were immediately transferred to the laboratory and sera were separated and stored at - 20 °C. Superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and malondialdehyde (MDA) concentrations were measured with commercial kits. RESULTS: The levels of SOD, GPX and CAT were significantly higher in the melatonin and anesthesia+melatonin groups compared to those of the control group at days 3 and 5. The level of antioxidant enzymes significantly decreased in the OHE group compared to that of other groups at days 3 and 5. The administration of melatonin increased the level of antioxidant enzymes in ovariohysterectomized dogs. Ovariohysterectomy significantly increased the concentration of MDA in comparison to that of other groups at day 3. Melatonin administration significantly decreased the level of MDA in melatonin, anesthetized, and ovariohysterectomized dogs at day 3. CONCLUSIONS: Administration of melatonin on day - 1, 0, 1, 2 and 3 modulate the oxidative stress induced by OHE in dogs by increasing antioxidant enzymes concentration and decreasing MDA levels.