Effect of gonadectomy on pain assessment in dogs undergoing orthopaedic stifle surgery.

Abstract

OBJECTIVE: To compare pain perception between gonadectomized and intact dogs. STUDY DESIGN: Blinded, prospective, cohort study. ANIMALS: A group of 74 client-owned dogs. METHODS: Dogs were divided into four groups: group 1-female/neutered (F/N), group 2-female/intact (F/I), group 3-male/neutered (M/N) and group 4-male/intact (M/I). Premedication consisted of intramuscularly administered acepromazine (0.05 mg kg) and morphine (0.2 mg kg), and subcutaneously administered carprofen (4 mg kg). Anaesthesia was induced with propofol (1 mg kgintravenously and supplementary doses to effect) and maintained with isoflurane in 100% oxygen. Intraoperative analgesia was achieved with fentanyl infusion (0.1 &#x3bc;g kgminute). Pain assessments [using the University of Melbourne Pain Scale (UMPS) and an algometer at the incision site (IS), parallel to the incision site (NIS), and on the contralateral healthy limb] were performed preoperatively, and at 1, 2, 4, 6, 9 and 20 hours after extubation. The time-standardised area under the curve (AUCst) for measurements was calculated and compared by performing a one-way multivariate analysis of variance (manova). Statistical significance was set at p < 0.05. RESULTS: Postoperatively, F/N exhibited higher pain than F/I, with estimated marginal means (95% confidence intervals) AUCstIS909 (672-1146) versus AUCstIS1385 (1094-1675) (p&#xa0;= 0.014), AUCstNIS1122 (823-1420) versus AUCstNIS1668 (1302-2033) (p&#xa0;= 0.024) and AUCstUMPS5.30 (4.58-6.02) versus AUCstUMPS4.1 (3.2-5.0) (p&#xa0;= 0.041). Similarly, M/N showed higher pain than M/I with AUCstIS686 (384-987) versus AUCstIS1107 (871-1345) (p&#xa0;= 0.031) and AUCstNIS856 (476-1235) versus AUCstNIS1407 (1109-1706) (p&#xa0;= 0.026), and AUCstUMPS6.0 (5.1-6.9) versus AUCstUMPS4.4 (3.7-5.2) (p&#xa0;= 0.008). CONCLUSIONS AND CLINICAL RELEVANCE: Gonadectomy affects pain sensitivity in dogs undergoing stifle surgery. Neutering status should be taken into consideration when planning individualized anaesthetic/analgesic protocols.