Does perioperative electroacupuncture reduce postoperative pain in dogs undergoing ovariohysterectomy?

Abstract

Introduction: This study aimed to investigate the analgesic efficacy of perioperative electroacupuncture in fifty-six healthy female dogs undergoing ovariohysterectomy as part of a catch-neuter-release project.

Materials and methods: Ten minutes after sedation with 20 μg/kg medetomidine combined with 0.3 mg/kg butorphanol intramuscularly, the dogs were randomly allocated into two groups and received either electroacupuncture (EA, n = 27) or sham acupuncture (C, n = 29) treatment for 10 min (after sedation until the end of the surgery) at 6 different acupuncture points LI-4 (Large intestine 4), LIV-3 (Liver 3), ST-36 (Stomach 36), SP-6 (Spleen 6) bilateral. After administration of 0.2 mg/kg meloxicam and anesthesia induction with 2 mg/kg ketamine intravenously, ovariohysterectomy was performed by the same experienced surgeon using a midline surgical approach in dorsal recumbency. Pain was evaluated by two blinded and independent anesthetists using the Short Form of the Multimodal Glasgow Composite Pain Scale (mCMPS-SF) before sedation (T0), and three (T3), six (T6), and 24 h (T24) after anesthesia induction.

Results: Postoperative pain scores did not differ significantly between the groups (p = 0.36), but increased significantly three (T3) (p = 0.001) and six (T6) (p = 0.001) hours after surgery compared to before sedation and 24 h postoperative in both groups. Three hours after surgery (T3), 89.4% and six hours postoperatively (T6), 71.4% of the dogs in both groups exceeded the analgesic intervention threshold of the mCMPS-SF, indicating the need for rescue analgesia.

Discussion: The results of the study indicate that perioperative electroacupuncture treatment did not improve postoperative pain in dogs undergoing ovariohysterectomy. Therefore, a 10-min electroacupuncture treatment may be insufficient to provide effective postoperative analgesia. The pain assessment in feral dogs was notably impacted by anxious behavior, which may have influenced the final outcome The pain threshold was exceeded in ¾ of the dogs in the early postoperative phase (T3, T6), suggesting that the widely used anesthesia protocol consisting of butorphanol, ketamine and medetomidine in combination with meloxicam may not provide long-lasting and sufficient pain relief.

Keywords: canine; electroacupuncture; multimodal analgesia; ovariohysterectomy; pain score.

Figure 1

In the electroacupuncture group the following acupoints were stimulated bilaterally to improve postoperative pain in dogs undergoing ovariohysterectomy: LI-4 (Large intestine 4), LIV-3 (Liver 3), ST-36 (Stomach 36), SP-6 (Spleen 6). 1 cun: The width of the last rib or the first tail vertebra is one cun. LI-4: Between the 2nd and 3rd metacarpal bones, at the midpoint of the 3rd metacarpal bone on the medial side. LIV-3: Between the 2nd and 3rd metatarsal bones, proximal to the metatarsophalangeal joint. ST-36: 0.5 cun lateral to the cranial crest of the tibia; in the belly of the cranial tibialis muscle (a long linear point). SP-6: 3 cun proximal to the tip of the medial malleolus in a small depression on the caudal border of the tibia (31).

Figure 2

Self-adhesive foam-wound pads (Animal Polsters, Snögg, Switzerland) covering acupoints were used in both groups to ensure blinding of the anesthetist.

Figure 3

Boxplots presenting the overall median pain scores of 56 female dogs undergoing ovariohysterectomy receiving an additional electroacupuncture treatment (EA) or a sham treatment (C) using the mGCPS-SF (scale 0–20) performed preoperatively (0), three (3), six (6) and 24 h postoperatively. Outliers are marked as individual points in the boxplot.

Figure 4

Median pain scores of 56 female dogs undergoing ovariohysterectomy receiving an additional electroacupuncture treatment (EA) or a sham treatment (C) between two different observers using the mGCPS-SF (Modified Glasgow Composite Pain Scale—Short Form; scale 0–20) at preoperative baseline (0 h) and at 3, 6, and 24 h postoperatively. Outliers are marked as individual points in the boxplot.