Comparing intramuscular ketamine with peri-incisional bupivacaine with or without ketamine in dogs undergoing hemilaminectomy

Objective

To investigate whether infiltrating bupivacaine with ketamine into the epaxial muscles improves quality and duration of analgesia perioperatively compared with bupivacaine alone or ketamine intramuscularly.

Study design

Prospective blinded randomized clinical study.

Animals

A group of 66 dogs randomized into three groups (n = 22).

Methods

Before surgery, bupivacaine 0.5% 2 mg kg^–1 alone (group B) or combined with ketamine 2 mg kg^–1 (group BK) was infiltrated peri-incisionally into the epaxial muscles. Group K received ketamine 2 mg kg^–1 injected intramuscularly into a cervical muscle without infiltration. Meloxicam 0.2 mg kg^–1 was given intravenously (IV) before moving to theatre. Cardiovascular variables: heart rate and systolic, mean and diastolic blood pressure were recorded. Intraoperative fentanyl 5 μg kg^–1 IV was administered if these variables increased by 20% from baseline. Fentanyl continuous infusion (5 μg kg^–1 hour^–1) was started if more than three boluses were required. The Glasgow Composite Pain Scale-Short Form was used pre- and postoperatively for acute pain assessment at different time intervals; methadone 0.2 mg kg^–1 IV was administered if scores were greater 5/20. Analgesia requirements, time to first administration, pain scores, total opioids interventions, need for sedation, first food intake and adverse effects were recorded. Continuous, normally distributed and non-normally distributed variables were analysed using ANOVA or Kruskal Wallis test, respectively.

Results

No significant difference was found for cardiovascular variables between groups over time, intra- or postoperative analgesia requirements, time to administration, pain scores total opioids, time to first food intake, sedation and occurrence of adverse effects.

Conclusions and clinical relevance

No difference in perioperative rescue analgesia was found between groups.