This study aimed to compare postoperative analgesia provided by either dipyrone or meloxicam and determine the hematological and biochemical effects in cats undergoing ovariohysterectomy. Thirty cats were premedicated with acepromazine and tramadol, induced with ketamine and propofol and maintained with sevoflurane and remifentanil. Postoperatively, the animals were randomly treated with either dipyrone, 20 mg/kg or 30 mg/kg (IV) every 12 hours for three days; or Meloxicam 0.1 mg/kg (IV) every 24 hours for three days (n = 10 per group). The animals were evaluated at 6, 12, 24, 30, 36, 48, 54 and 60 hours using the multidimensional scale of UNESP, Botucatu, in which: 0, absence of pain; 1 to 8, mild pain; and 9 to 30, moderate to severe pain. Blood samples were collected before anesthesia and 24 and 96 hours after treatments, to perform blood count, aminotransferase alanine, creatinine, urea, alkaline phosphatase, albumin, and prothrombin and thromboplastin times. Statistical analysis was performed by ANOVA test for continuous variables and Chi square for qualitative variables at each time, between the study groups and within each group. Differences were considered significant when p <0.05. The results showed no laboratory abnormalities attributable to treatment, nor significant differences between groups. Pain scores were lower (p <0.05) with dipyrone at 12, 24, 30, 36, 54 and 60 hours, compared with meloxicam. There were no significant differences in pain scores between dipyrone doses. No rescue analgesia was necessary in any of the groups. The number of patients with no pain in the dipyrone group was higher than in the meloxicam group at all times, but significantly differences were not observed. Dipyrone compared with meloxicam promotes effective analgesia in cats undergoing ovariohysterectomy.