The challenge of evaluating pain and a pre-incisional local anesthetic block

Carolyn M McKune; Peter J Pascoe; B Duncan X Lascelles; Philip H Kass

doi:10.7717/peerj.341

The challenge of evaluating pain and a pre-incisional local anesthetic block

PeerJ. 2014 Apr 10:2:e341. doi: 10.7717/peerj.341. eCollection 2014.

Authors

Carolyn M McKune¹, Peter J Pascoe¹, B Duncan X Lascelles², Philip H Kass³

Affiliations

¹ Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California , Davis, CA , USA.
² Comparative Pain Research Laboratory, Department of Clinical Sciences & Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University , Raleigh, NC , USA.
³ Department of Population Health and Reproduction, School of Veterinary Medicine, University of California , Davis, CA , USA.

Abstract

Background. Our objective was to test the effectiveness of a local anesthetic line block administered before surgery in reducing postoperative pain scores in dogs undergoing ovariohysterectomy (OVHX). Methods. This study is a prospective, randomized, blinded, clinical trial involving 59 healthy female dogs. An algometric pressure-measuring device was used to determine nociceptive threshold, and compared to three subjective pain scales. Group L/B received a line block of lidocaine (4 mg/kg) and bupivacaine (1 mg/kg) subcutaneously in the area of the incision site and saline subcutaneously as premedication; group L/BM (positive control) received a similar block and morphine (0.5 mg/kg) subcutaneously for premedication; and group SS (negative control) received a saline line block and saline premedication. Criteria for rescue analgesia were defined before the study. Dogs were assessed prior to surgery, at extubation (time 0) and at 2, 4, 6, 8 and 24 h post-recovery. The data were analyzed with one-way ANOVA, and a Split Plot Repeated Measures ANOVA with one grouping factor and one repeat factor (time). P < 0.05 was considered statistically significant. Results. Approximately 33% of dogs required rescue analgesia at some point during the study, with no significant difference between groups. There was no significant difference between treatment groups with any assessment method. Conclusions. As there were no statistically significant differences between positive and negative controls, the outcome of this technique cannot be proven.

Keywords: Bupivacaine; Dog; Lidocaine; Local anesthesia; Pain assessment.

Grants and funding

This work was funded by the Center for Companion Animal Health, University of California (Davis). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.