Evaluation of the perioperative analgesic effects of grapiprant compared with carprofen in dogs undergoing elective ovariohysterectomy

OBJECTIVE To evaluate and compare postoperative analgesic effects of grapiprant and carprofen in dogs undergoing ovariohysterectomy. ANIMALS 42 sexually intact female healthy dogs (< 35 kg and 0.5 to 7 years old) were enrolled. PROCEDURES In a masked, randomized, noninferiority clinical trial, dogs received either 2 mg/kg of grapiprant or 4.4 mg/kg of carprofen orally 2 hours prior to ovariohysterectomy. Postoperative pain was assessed using the Glasgow Composite Pain Scale-Short Form (GCPS-SF) at extubation and 2, 4, 6, 8, 18, and 24 hours postextubation and compared to baseline. After each pain scoring, mechanical nociceptive testing with von Frey monofilaments (vF) was performed to assess hyperalgesia. Hydro- morphone (0.05 mg/kg, IM) was administered to any dog with a GCPS-SF of >= 5/24. The noninferiority limit (NI) for the GCPS-SF was Delta = 3. The NI for vF was Delta = -0.2. Following noninferiority, a mixed-effect ANOVA and post hoc comparisons were made with the Tukey correction method (P < .05). RESULTS 3 dogs required rescue analgesia and were excluded from statistical analysis. Of the remaining 39 dogs, the upper CI for GCPS-SF was below the NI of 3 and the lower CI for vF was greater than the NI of -0.2, indicating noninferiority of grapiprant as compared to carprofen. There was no difference between treatment (P = .89) nor treatment by time (P = .62) for GCPS-SF. There was no difference between groups at any time point or over time when vF were used. CLINICAL RELEVANCE Our study results support the use of grapiprant as an analgesic alternative to carprofen in dogs undergoing ovariohysterectomy.