Postoperative analgesic efficacy of pharmacopuncture at Zusanli (ST-36) or intramuscular morphine in bitches undergoing unilateral total mastectomy: a randomized clinical trial

ABSTRACT This study aimed to compare the postoperative analgesic efficacy of intramuscular morphine and morphine pharmacopuncture at the Zusanli acupoint (ST-36) in female dogs undergoing unilateral total mastectomy. Sixteen client-owned bitches were randomly assigned to a double-blinded clinical trial and received either intramuscular morphine (0.5mg/kg; MORP) or pharmacopuncture with a microdose of morphine (0.05mg/kg) at ST-36 (ZUS36). Pain assessments were conducted at T0-T24 hours using the Visual Analog Scale (VAS) and the short-form Glasgow Composite Pain-Scale (CMPS-SF), evaluated by an experienced (EE) and a non-experienced assessor (NEE). Both protocols provided effective analgesia, with no significant differences in postoperative pain scores. The number of rescue interventions based on VAS assessments was 8 for MORP and 6 for ZUS36, while CMPS-SF evaluations recorded 15 and 13 interventions, respectively, for EE. The NEE overestimated rescue analgesia requirements in VAS assessments (11 rescues for MORP vs. 7 for ZUS36) but underestimated them in CMPS-SF evaluations (13 for MORP vs. 11 for ZUS36). A strong correlation was observed between EE and NEE in CMPS-SF (r=0.940) and VAS (r=0.748). Pharmacopuncture at ST-36 provided analgesia comparable to intramuscular morphine, highlighting its potential as an adjuvant analgesic strategy to reduce opioid requirements in canine mastectomy.