Emprego da detomidina na contenção farmacológica e na anestesia intravenosa contínua com cetamina ou dextrocetamina em cadelas.

Abstract

Anesthesia promoted by the association of detomidine and ketamine or dextroketamine by continuous intravenous route in the canine species, and the applicability of this anesthesia or the use of detomidine associated with other drugs in ovarian-hysterectomy (OH) surgery were evaluated and the thesis being divided into three chapters. In the first, the pharmacological restraint and the effects on physiological parameters promoted by detomidine-midazolam-pethidine or xylazine-ketamine combinations were evaluated in female dogs submitted to OH. Sixteen dogs were used in two groups: detomidine, midazolam and pethidine (GDMP), 0.04 mg/kg, 0.3 mg/kg and 3 mg/kg, respectively, intramuscularly (IM); xylazine and ketamine (GXC), 1 mg/kg and 20 mg/kg, respectively, IM. Epidural anesthesia was performed in both groups. Heart and respiratory rates, electrocardiography, temperature, systolic arterial pressure, latency and anesthetic periods, myorelaxation, recovery and pharmacological restraint were evaluated. There was no hypotension, bradycardia or severe hypothermia, although atrioventricular block was observed in both groups. The recovery was excellent, with adequate protocols for pharmacological containment in female dogs. In the second chapter, we compared the cardiorespiratory and anesthetic effects promoted by the association of detomidine and ketamine or dextroketamine in continuous intravenous administration in eight female dogs submitted to two protocols: GCD (racemic ketamine + detomidine) - induction and anesthetic maintenance with ketamine racemic at doses of 5 mg/kg, IV, and 20 mg/kg/h, respectively; and GDD (dextroketamine + detomidine) - induction and anesthetic maintenance with dextroketamine, at doses of 3.5 mg/kg, IV, and 14 mg/kg/h, respectively. The preanesthetic medication was performed with detomidine, 0.02 mg/kg, IM, and the infusion was associated with that of detomidine, at a dose of 30 μg/kg/h, IV. Heart rate, mean arterial pressure, respiratory rate, temperature, myorelaxation, electrocardiogram, hemogasometry, analgesia, quality and duration of recovery were recorded. Bradycardia, hypotension, hypertension, electrocardiographic abnormalities, arrhythmias and respiratory acidosis were observed. It was concluded that racemic ketamine and dextrocetamine, used in a ratio of 1.5: 1, and associated with detomidine by continuous intravenous infusion, cause similar cardiorespiratory and anesthetic effects in dogs. In the third chapter, we evaluated the cardiorespiratory and anesthetic effects promoted by the combination of detomidine and dextroketamine, by continuous intravenous route, in eight female dogs premedicated with midazolam and morphine and submitted to OH, and the same parameters were evaluated as in chapter two. Cortisol and glucose levels were measured. There was bradycardia, bradypnoea, hypotension, electrocardiographic alterations, arrhythmias and respiratory acidosis with hypoxemia. Cortisol levels increased significantly after pinching the ovarian pedicles and after dermorrhaphy. Glucose levels increased significantly after dermorrhaphy, concluding that continuous intravenous anesthesia with dextrocetamine and detomidine causes respiratory depression and cardiovascular changes and is not sufficient to abolish pain caused by OH. It could be concluded that the use of detomidine in dogs can be considered an option, as long as there is electrocardiographic monitoring. When associated with midazolam, pethidine and epidural anesthesia, detomidine can be used in the pharmacological restraint of female dogs submitted to OH. Continuous intravenous anesthesia with racemic ketamine or dextroketamine and detomidine should be accompanied by supplementation of oxygen and by complementation of analgesia.