Evaluation and comparison of postoperative analgesic effects of dexketoprofen and methadone in dogs.

OBJECTIVE: To evaluate and compare the analgesic efficacy and adverse effects of dexketoprofen and methadone using a noninferiority trial, during the first 24 postoperative hours in dogs undergoing orthopaedic surgery. STUDY DESIGN: Randomized, blinded clinical study. ANIMALS: A total of 38 healthy dogs undergoing orthopaedic surgery. METHODS: Dogs were premedicated with dexmedetomidine [1 µg kg-1 intravenously (IV)] followed by dexketoprofen (1 mg kg-1 IV; group DK) or methadone (0.2 mg kg-1 IV; group M). Anaesthesia was induced with propofol and maintained with isoflurane in 60% oxygen. Postoperatively, dexketoprofen was administered every 8 hours (group DK) and methadone every 4 hours (group M). Analgesia was assessed at baseline and at 1, 2, 4, 6, 18 and 24 hours after extubation using a dynamic and interactive visual analogue scale (DIVAS), the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF), mechanical wound thresholds (MWTs) and plasma cortisol levels. If CMPS-SF score was ≥5, rescue analgesia was administered. Data were analysed using a general linear mixed model, Mann-Whitney U test and chi-squared test as appropriate; a p value <0.05 was considered significant. RESULTS: The CMPS-SF and DIVAS scores were significantly higher in group M compared with group DK and remained higher for a longer period in group M, although the differences were not clinically significant. No significant differences were found in MWT assessment between groups. Plasma cortisol level significantly increased 2 hours after extubation, without significant differences between treatments. Rescue analgesia was administered to three animals (one in group DK; two in group M). CONCLUSION AND CLINICAL RELEVANCE: We conclude that 1 mg kg-1 IV dexketoprofen administered every 8 hours during the first 24 hours postoperatively is noninferior to methadone in controlling pain after orthopaedic surgery in dog, although frequent pain assessments are recommended to adjust the analgesia plan.

Effect of dexmedetomidine constant rate infusion on the bispectral index during alfaxalone anaesthesia in dogs.

OBJECTIVE: To assess the effect of two rates of infusion of dexmedetomidine on the bispectral index (BIS) in dogs anaesthetized with alfaxalone constant rate infusion (CRI). STUDY DESIGN: Prospective, randomized, 'blinded' experimental study. ANIMALS: Six healthy Beagles (three females and three males). METHODS: Dogs received as premedication saline (group D0), 1 µg kg(-1) (group D1) or 2 µg kg(-1) (group D2) dexmedetomidine, intravenously (IV). Anaesthesia was induced with alfaxalone (6 mg kg(-1) to effect IV) and maintained with alfaxalone at 0.07 mg kg(-1)  minute(-1) and a CRI of saline (D0) or dexmedetomidine 0.5 µg kg(-1)  hour(-1) (D1) or 1 µg kg(-1)  hour(-1) (D2) for 90 minutes. BIS, electromyography (EMG), signal quality index (SQI) and suppression ratio (SR) were measured at 10 minute intervals and the median values were calculated. Nociceptive stimuli were applied every 30 minutes and BIS and cardiorespiratory values were compared before and after stimuli. Cardiorespiratory parameters were recorded throughout the study. RESULTS: BIS and EMG values differed significantly among groups, being lower in D2 (71 ± 8) than in D0 (85 ± 10) and D1 (84 ± 9). SQI was always over 90% and SR was zero throughout all the treatments. There were no significant differences between pre- and post-stimulus values of BIS, EMG and SQI for any treatment, although in D0 and D1, heart rate, respiratory rate and arterial pressures increased significantly after the nociceptive stimulus. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of dexmedetomidine (2 µg kg(-1)  + CRI 1 µg kg(-1)  hour(-1) ) decreases the BIS values and avoids the autonomic responses of a nociceptive stimulus during alfaxalone anaesthesia at 0.07 mg kg(-1)  minute(-1) in dogs. However, further studies are needed to verify whether this combination produces an adequate degree of hypnosis under surgical situations.

Comparison of the cardiopulmonary parameters after induction of anaesthesia with alphaxalone or etomidate in dogs.

OBJECTIVE: To compare the cardiorespiratory effects and quality of induction of and recovery from anaesthesia following etomidate or alphaxalone-HPCD IV. STUDY DESIGN: Randomized 'blinded' cross-over study. Twenty-four hours was allowed between phases. ANIMALS: Eight healthy adult Beagles (four male, four female). METHODS: Dogs were anaesthetized with sevoflurane for instrumentation, then allowed to awake. They then received etomidate (treatment E) or alphaxalone-HPCD (treatment A) intravenously to effect. Heart rate (HR), body temperature, invasive arterial pressures (AP), systemic vascular resistance index (SVRI), stroke volume index, cardiac index (CI), contractility, respiratory rate, central venous pressure, and capnometry were obtained before anaesthetic induction (baseline), 30 seconds and 1 minute after induction, after intubation, one minute after intubation, and for every 5 minutes afterwards until the dog began to swallow and the trachea was extubated. Arterial bloods were taken for analyses before induction, after intubation and every 10 minutes thereafter. The dogs breathed room air. The quality of induction of and recovery from anaesthesia were scored categorically. Statistical analyses used anova for repeated measures, paired t-tests or Wilcoxon signed rank-test as relevant. Significance was set at p < 0.05. RESULTS: The induction doses required were (mean ± SD) 2.91 ± 0.41 mg kg(-1) and 4.15 ± 0.7 mg kg(-1) for treatment E and A respectively. No significant changes in cardiovascular parameters were observed with treatment E. Treatment A resulted in statistically significant increases in HR and CI and reductions of APs and SVRI. Time to extubation was longer with treatment A (25 ± 7 minutes) than with treatment E (17 ± 4 minutes). Dogs became hypoxic with both treatments. The quality of induction and recovery were excellent with treatment A, but significantly less satisfactory with treatment E (recovery score, treatment E median 1, range 0-2; treatment A median 0, range 0-1). CONCLUSIONS AND CLINICAL RELEVANCE: Alphaxalone-HPCD caused significant tachycardia and increase in CI, and statistically (but not clinically) significant decreases in APs and SVRI. Etomidate caused no statistically significant cardiovascular changes. Quality of recovery was better with alfaxalone-HPCD. Both agents caused short-lived hypoxia, and oxygen supplementation is advisable.