A comparison between pre-operative carprofen and a long-acting sufentanil formulation for analgesia after ovariohysterectomy in dogs

Objective To assess the analgesic efficacy and adverse effects of a novel, long-acting sufentanil preparation in dogs undergoing ovariohysterectomy (OHE). Study design Blinded, positively controlled, randomized field trial with four parallel treatment groups. Animals Eighty client owned dogs undergoing elective OHE randomly allocated into four treatment groups (each n = 20). Materials and methods Three groups received intramuscular (IM) sufentanil (at 10, 15 and 25 mug kg-1, respectively) and the control group received subcutaneous (SC) carprofen 4 mg kg-1 SC plus acepromazine 0.05 mg kg-1 IM as pre-anaesthetic medication. OHE was performed under thiopental/halothane anaesthesia. Visual Analogue Scale (VAS) scores for pain and sedation were awarded and mechanical nociceptive thresholds were measured at the wound and hock before surgery and up to 24 hours after tracheal extubation. Serum cortisol was measured before surgery, during surgery and up to 24 hours after tracheal extubation. Animals with inadequate post-operative analgesia were given rescue medication. Results In the carprofen group, VAS pain scores were significantly higher, wound tenderness was greater and requirement for rescue analgesia was more than in the sufentanil-treated groups. Sufentanil produced dose dependent analgesia and sedation. All treatment groups showed similar patterns of change for cortisol concentrations. Use of the sufentanil preparation was associated with a relatively high incidence of adverse events. Conclusions The long-acting preparation of sufentanil provided excellent post-operative analgesia that was significantly better than that provided by carprofen. However, use of this formulation, in the anaesthetic technique used in the study, resulted in a relatively high incidence of adverse effects. Clinical relevance Full mu (MOP) opioid agonists provide significantly better post-operative analgesia than nonsteroidal anti-inflammatory drugs after moderately painful surgery. However, the widely recognized adverse effects of opioids may preclude the use of these agents.