Analgesic efficacy of an ultrasound-guided transversus abdominis plane block with bupivacaine in cats: a randomised, prospective, masked, placebo-controlled clinical trial.

OBJECTIVES: This randomised, prospective, masked clinical trial evaluated the postoperative analgesic efficacy of an ultrasound-guided transversus abdominis plane block (TAPB) with bupivacaine in cats undergoing ovariohysterectomy. METHODS: Thirty-two healthy adult female cats undergoing elective ovariohysterectomy were randomised to undergo TAPB with bupivacaine (treatment group [TG], n = 16) vs placebo (control group [CG], n = 16) in addition to preoperative analgesia with buprenorphine (0.02 mg/kg IM). All patients received a general anaesthetic and, before surgical incision, a bilateral two-point (subcostal and lateral-longitudinal) TAPB was performed using 1 ml/kg bupivacaine 0.25% (0.25 ml/kg/point) or saline. Each cat was assessed by a blinded investigator before premedication (0 h) and at 1, 2, 3, 4, 8, 10 and 24 h postoperatively using the UNESP-Botucatu Feline Pain Scale - short form. Buprenorphine (0.02 mg/kg IV) and meloxicam (0.2 mg/kg SC) were administered when pain scores were ⩾4/12. Ten hours postoperatively, meloxicam was administered to cats that did not receive rescue analgesia. Statistical analysis included Student's t-tests, Wilcoxon tests and χ2 tests, and a linear mixed model with Bonferroni corrections (P <0.05). RESULTS: Of the 32 cats enrolled, three in the CG were excluded from the analysis. The prevalence of rescue analgesia was significantly higher in the CG (n = 13/13) than in the TG (n = 3/16; P <0.001). Only one cat in the CG required rescue analgesia twice. Pain scores were significantly higher in the CG compared with the TG at 2, 4 and 8 h postoperatively. Mean ± SD pain scores were significantly higher in the CG, but not in the TG, at 2 (2.1 ± 1.9), 3 (1.9 ± 1.6), 4 (3.0 ± 1.4) and 8 h postoperatively (4.7 ± 0.6) than at 0 h (0.1 ± 0.3). CONCLUSIONS AND RELEVANCE: A bilateral ultrasound-guided two-point TAPB with bupivacaine in combination with systemic buprenorphine provided superior postoperative analgesia than buprenorphine alone in cats undergoing ovariohysterectomy.

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 µg/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.

Feasibility and reliability of electrical, mechanical and thermal nociceptive testing and assessment of diffuse noxious inhibitory control in dogs.

PURPOSE: Quantitative sensory testing has been used to assess the somatosensory system. This study aimed to evaluate the feasibility and reliability of electrical (ENT), mechanical (MNT) and thermal (TNT) nociceptive testing and the effect of a conditioning stimulus on MNT. PATIENTS AND METHODS: Sixteen healthy client-owned dogs were included in this study. Stimulation was applied bilaterally to the dorsal and plantar aspect of the metacarpus and metatarsus respectively, using transcutaneous electrical stimulator, algometry and a cold nociceptive device in a randomized order until a behavior response was observed or a cut-off reached. Tests were performed twice (60 seconds apart) by two observers. Retesting was performed 5 hours later. The diffuse noxious inhibitory control was tested by comparing MNT pre- and post-conditioning stimuli. Sham-testing was performed for ENT and TNT. Statistical analysis included linear model and intra-class correlation coefficient (P<0.05). RESULTS: Feasibility was 99% (ENT), 93.5% (MNT) and 93.6% (TNT). Data for TNT were not analyzed due to inconsistent results. Mean ± SD were 48±22.6 mA (ENT) and 11.9±3.5 N (MNT). MNT was higher for thoracic than for pelvic limbs (P=0.002). Conditioning stimulus increased MNT (P=0.049). Inter-observer reliability was 91.4% (ENT) and 60.9% (MNT). False-positive responses were 15% (ENT) and 35.7% (TNT). CONCLUSION: ENT was feasible, repeatable and superior to MNT and TNT. The assessment of the diffuse noxious inhibitory control with a conditioning stimulus showed promising results in dogs. These tools could be used in naturally-occurring disease to provide insight on their underlying mechanisms and therapeutics.