Multicenter, randomized controlled trial of pain-related behaviors following routine neutering in dogs

OBJECTIVE: To evaluate the degree of postoperative pain in dogs undergoing elective castration or ovariohysterectomy (OHE); determine whether an association exists between surgeon experience, incision length, or surgery duration and degree of postoperative pain; and determine whether analgesic treatment decreases expression of postoperative pain behaviors. DESIGN: Randomized controlled clinical trial. ANIMALS: 426 client-owned dogs undergoing OHE or castration. PROCEDURES: Dogs underwent OHE or castration performed by an experienced veterinarian or a fourth-year veterinary student. Dogs were randomly assigned to 1 of 4 treatment groups: no perioperative analgesic treatment (n = 44), preoperative administration of morphine (144), preoperative administration of nalbuphine (119), and postoperative administration of ketoprofen (119). Dogs were evaluated while in the hospital before anesthesia and for 4 hours after surgery and once a day at home for 3 days after surgery. RESULTS: Dogs in all 4 groups had significant increases in overall pain scores after surgery, compared with baseline scores. There were significant differences among groups, with control dogs having significantly higher increases in overall pain scores than dogs in the other groups. Factors that did not influence the frequency or severity of pain-related behaviors included breed, individual hospital, anesthetic induction protocol, surgeon experience, and duration of surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that dogs expressed behaviors suggestive of pain following OHE and castration, that analgesic treatment mitigated the expression of pain-related behaviors, and that surgeon experience and surgery duration did not have any effect on expression of pain-related behaviors.