Effectiveness of pre-peritoneal continuous wound infusion with lidocaine for pain control following ovariohysterectomy in dogs.

This study compared the post-operative analgesic efficacy of continuous lidocaine administration with that of intramuscular (IM) methadone in dogs undergoing ovariohysterectomy. Thirty-eight dogs were divided randomly into two groups. Following surgery, the lidocaine group (L) received a continuous lidocaine infusion (2 mg/kg/h) through a wound catheter inserted in the pre-peritoneal space; the control group (C) received methadone (0.2 mg/kg IM). A dynamic and interactive visual analogue scale (DIVAS), the Scale-Form Glasgow Composite Measure Scale (CMPS-SF), mechanical wound thresholds, heart rate, respiratory rate and blood pressure were assessed pre-operatively and 2, 4, 6, 18, and 24 h after surgery. The presence of the wound catheter prevented the evaluator from remaining blinded to group allocations. Plasma lidocaine and cortisol levels were measured 2, 6, 18, and 24 h after surgery. There were no intergroup differences in any pain assessment scale scores at any time point. Stable intravenous lidocaine levels were observed. Four animals in the control group but none in the lidocaine group required rescue analgesia. There were no differences in complication rates between groups. Continuous locoregional lidocaine delivered via a wound catheter between the parietal peritoneum and abdominal muscle offers effective analgesia in dogs during ovariohysterectomy and appears to be a promising analgesic option in veterinary surgery.