EXPRESS: Efficacy of combined grapiprant and tapentadol for analgesia in cats undergoing elective ovariohysterectomy

This study aimed to evaluate the effects on intraoperative physiological parameters and adverse event occurrence and the post-operative analgesic efficacy of combined grapiprant and tapentadol in cats undergoing elective ovariohysterectomy, through two multidimensional pain scales. Sixty mixed-breed female cats were enrolled in a randomized, prospective, blinded study. The animals were evenly distributed into four groups (n = 15 per group). Fifty-one animals completed the study, the control group received placebo (CON, n = 11), while the grapiprant group (GRA, n = 13) received grapiprant (3.8 ± 0.5 mg/kg), the tapentadol group (TAP, n = 13) received tapentadol (5.3 ± 1.2 mg/kg), and the grapiprant-tapentadol group (GT, n = 13) received a combination of grapiprant (4.2 ± 0.5 mg/kg) and tapentadol (5 ± 0.6 mg/kg), orally one hour prior to initiation of the standardized anaesthesia protocol and surgical procedure. Physiological parameters were monitored during surgery, and post-operative pain was assessed for 6 hours following extubation using the UFESP-SF and the FGS, administered by two treatment-blinded evaluators. No adverse effects or statistically significant differences in physiological parameters were observed between groups. The assessment of pain scores showed good reliability, with Intraclass correlation coefficient values of 0.89 for the FGS and 0.91 for the UFESP-SF, supporting inter-rater agreement for both instruments. At 3 hours postoperatively, FGS scores differed significantly between CON and GT groups (p = 0.0363). Rescue analgesia requirements also varied among groups (p = 0.0110): GT required rescue at 3 hours, compared with 1 hour in CON (p = 0.0007) and 2 hours in GRA (p = 0.0058). The results of this study showed that the analgesic effect of the grapiprant-tapentadol combination lasted up to 3 hours in the postoperative period, which was longer than the 2 hours of grapiprant and tapentadol alone, without compromising intraoperative physiological stability.