Objective: To determine the cardiovascular effects of a proprietary l-methadone/fenpipramide combination (Polamivet) alone and in addition to acepromazine in dogs.
Study design: Prospective, randomized, experimental crossover study.
Animals: Five adult healthy Beagle dogs (one male and four females, weighing 12.8-16.4 kg).
Methods: Dogs were instrumented for haemodynamic measurements whilst anaesthetized with isoflurane. Three hours after recovery dogs received 0.025 mg kg(-1) acepromazine (AP) or saline (SP) IM followed by 0.5 mg kg(-1) L-methadone/ 0.025 mg kg(-1) fenpipramide IV after 30 minutes. Cardiac output using thermodilution, heart rate, mean arterial pressure (MAP), central venous pressure (CVP), mean pulmonary artery pressure (MPAP), pulmonary artery occlusion pressure (PAOP), haemoglobin concentration, arterial and mixed-venous blood gas analysis were measured and sedation evaluated at baseline (BL), 30 minutes after acepromazine or saline IM (A/S), 5 minutes after L-methadone/fenpipramide IV application (35), every 15 minutes for 1 hour (50, 65, 80, 95 minutes) and every hour until baseline cardiac output was regained. Standard cardiovascular parameters were calculated. Data were analyzed by repeated measures anova and paired t-tests with p < 0.05 considered significant.
Results: Baseline measurements did not differ. Cardiac index decreased after acepromazine administration in treatment AP (p = 0.027), but was not significantly influenced after l-methadone/fenpipramide injection in either treatment. In both treatments heart rate did not change significantly over time. Stroke volume index increased after A/S in both treatments (p = 0.049). Systemic vascular resistance index, MAP, CVP, MPAP, and pulmonary vascular resistance index did not change significantly after either treatment and did not differ between treatments. Dogs were deeply sedated in both treatments with a longer duration in treatment AP.
Conclusions and clinical relevance: In healthy dogs the dose of l-methadone/fenpipramide used in this study alone and in combination with acepromazine induced deep sedation without significant cardiovascular changes.
© 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.