Randomised, prospective, blinded, clinical trial of opioid-free injectable anaesthesia with or without multimodal analgesia in kittens undergoing ovariohysterectomy

Objectives This study compared an opioid-free injectable anaesthetic protocol with or without multimodal analgesia in kittens undergoing ovariohysterectomy. Methods In this prospective, randomised, blinded, clinical trial, 29 healthy kittens (mean +/- SD weight 1.55 +/- 0.46 kg; aged 10 weeks to 6 months) were included. Anaesthesia was performed with an intramuscular injection of ketamine (4 mg/kg), dexmedetomidine (40 mu g/kg) and midazolam (0.25 mg/kg). In the multimodal group (MMG), cats (n = 14) received meloxicam (0.1 mg/kg SC) and intraperitoneal bupivacaine 0.25% (2 mg/kg), whereas the same volume of saline was administered in the control group (CG; n = 15). Atipamezole (0.4 mg/kg IM) was given 15 mins after ovariohysterectomy. Postoperative pain was assessed using the UNESP-Botucatu multidimensional feline pain assessment scale - short form. Rescue analgesia (buprenorphine 0.02 mg/kg IM in MMG/CG and meloxicam 0.1 mg/kg SC in CG) was administered if pain scores were > 4/12. Soft food intake (after 2 and 60 mins) was evaluated at specific time points postoperatively. Statistical analyses were performed with linear models and post-hoc pairwise comparison with Benjamini-Hochberg corrections (P <0.05). Results The prevalence of rescue analgesia was higher in the CG (n = 15/15) than the MMG (n = 1/14; P <0.001). Pain scores at 1 h, 2 h and 4 h postoperatively were higher in the CG (4.1 +/- 2.8, 4.8 +/- 3.0 and 5.3 +/- 1.2, respectively) than in the MMG (1.6 +/- 1.0, 1.1 +/- 1.0 and 0.9 +/- 0.8, respectively; P <0.001). Food intake (%) at 1 h postoperatively was higher in the MMG after 2 and 60 mins (10.4 +/- 9 and 71.9 +/- 29, respectively) than in the CG (1.4 +/- 2 and 13.9 +/- 7, respectively; P <0.001). Conclusions and relevance This opioid-free protocol using multimodal analgesia produced adequate postoperative pain relief, while almost eliminating the need for rescue analgesia in kittens undergoing ovariohysterectomy. Pain decreased food intake.