OBJECTIVE: To evaluate the effects of perioperative oral administration of tramadol, firocoxib, and a tramadol-firocoxib combination on signs of pain and limb function after tibial plateau leveling osteotomy in dogs. DESIGN: Randomized, blinded, prospective clinical trial. ANIMALS: 30 adult client-owned dogs with unilateral cranial cruciate ligament disease. PROCEDURES: Dogs were allocated into 3 treatment groups (tramadol, firocoxib, and a tramadol-firocoxib combination). Signs of pain (short-form Glasgow composite measure pain scale), serum cortisol concentrations, and limb function (pressure platform gait analysis) were recorded at several time points before surgery and through 3 days after surgery. Outcome measures were compared among groups. RESULTS: A significantly greater number of dogs in the tramadol group (8/10 dogs) had a pain score > 6 after surgery, compared with the other groups. No significant differences were detected in the pain scores between the firocoxib and the tramadol-firocoxib combination groups. There were no significant differences in serum cortisol concentrations among the 3 groups. Limb function was significantly decreased for dogs in the tramadol group on days 1 and 2 after surgery and in the firocoxib group on day 1 after surgery. Although limb function decreased for dogs in the tramadol-firocoxib combination group, the change was not significant for any day after surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs that received firocoxib orally, alone or in combination with tramadol, had lower pain scores, lower rescue opiate administration, and greater limb function than dogs that received only tramadol. When used alone, oral administration of tramadol may not provide sufficient analgesic efficacy to treat dogs with pain after orthopedic surgical procedures.