Electrocardiographic evaluation of dogs submitted to pre-anesthetic medication with acepromazine/meperidine or acepromazine/ methadone

Abstract

The percentage of heart disease patients who seek veterinary hospitals grows annually, as does the increase in surgical procedures, making it essential to improve anesthetic techniques as well as applied protocols. Pre-anesthetic medications can promote electrical changes in the cardiovascular system. These effects can be related to electrical and heart rate changes. Thus, the objective was to evaluate cardiac changes in two pre-anesthetic medication protocols through electrocardiography exams. Four dogs of both sexes were used, aged between 9 months to 4 years, average weight 12.75 kg, the animals were divided into 2 groups consisting of 2 animals each: Group AMT (acepromazine hydrochloride at a dose of 0.05 mg/kg associated with methadone, at a dose of 0.4 mg/kg, intramuscularly) and Group AMP (acepromazine hydrochloride at a dose of 0.05 mg/kg associated with meperidine, at a dose of 4 mg/kg, intramuscularly). Two-step electrocardiograms were performed, the first before the administration of drugs (T0) for each group and the second 15 minutes after the administration of pre-anesthetic drugs (T15). The AMP group showed greater changes in heart rate and also electrocardiographic changes such as bradycardia and sinus arrhythmia, which did not occur in the AMT group. The association of acepromazine and methadone in pre-anesthetic medication showed less cardiac changes, not promoting electrocardiographic alterations.