Background: This study evaluated the impact of intra-abdominal lidocaine and systemic meloxicam, alone and in combination, on oxidative stress biomarkers in healthy dogs undergoing elective ovariohysterectomy (OHE). Methods: Twenty-eight female dogs presenting to the Aydın Adnan Menderes University Veterinary Teaching Hospital were randomly assigned to one of four groups (n = 7 each): Control (OHE only), Lidocaine (1 mg/kg sprayed intraperitoneally at surgical sites), Meloxicam (0.2 mg/kg SC post-closure), and Lidocaine + Meloxicam (both treatments as above). Blood was sampled pre-operatively and at 2, 12, and 24 hours post-surgery. Serum concentrations of malondialdehyde (MDA), catalase (CAT), and glutathione peroxidase (GSH-Px) were quantified as indices of lipid peroxidation and antioxidant capacity. Results: In the combined-treatment group, MDA, CAT, and GSH-Px levels declined significantly over time, indicating attenuated oxidative stress. In contrast, lidocaine alone produced a significant time-dependent decrease only in CAT activity, while meloxicam alone did not significantly alter any marker. Conclusions: These findings suggest that the synergistic use of intraperitoneal lidocaine with systemic meloxicam more effectively mitigates postoperative oxidative stress than either agent alone, and may represent a beneficial analgesic–antiinflammatory strategy in canine OHE.