The purpose of this study was to assess the efficacy of grapiprant combined with metamizole for postoperative analgesia of healthy queens undergoing elective ovariohysterectomy, as well as the effects of both drugs on laboratory variables of blood and urine samples. Twenty-six mixed-breed adult queens deemed healthy based on clinical examination and scheduled for elective ovariohysterectomy were randomly allocated in three groups comprising three analgesia protocols: MET, metamizole at 25 mg/kg q8 hours (n=8); GRA, grapiprant at 2 mg/kg q24 hours (n=10); and GRAMET, grapiprant at 2 mg/kg q24 hours + metamizole 25 mg/kg q8 hours (n=8). Drugs were given orally in all groups 2 hours prior to extubation. Postoperative pain was assessed using multidimensional pain scales (UNESP and Glasgow) adapted for cats. Evaluations were carried out preoperatively (baseline) and 1, 3, 6, 8, 12 and 24 hours (T1, T3, T6, T8, T12 and T24, respectively) postoperatively. Venous blood samples were obtained at baseline and 24 hours following administration of treatment drugs for complete blood count and serum analysis (ALT, AST, GGT, ALP, creatinine, and urea). Urine samples were obtained at baseline and 24 hours following extubation for urinalysis. Blood glucose was assessed at baseline and 1 hour following extubation. Pain scores differed significantly over time among the three groups with both scales. Rescue analgesia was predominantly necessary within 3 hours following surgery (87.5% for MET, 50.0% for GRA and 62.5% for GRAMET). Lowest pain scores were found in MET and GRAMET as of T3 postoperatively. There were no changes in blood and urine variables throughout the study. Blood glucose increased in all groups at T1 compared with baseline. While metamizole and grapiprant were well tolerated in this study either given alone or in combination, postoperative analgesia was insufficient in healthy queens subjected to elective ovariohysterectomy. Neither drug was associated with any significant changes on laboratory variables over 24 hours of postoperative evaluation.