This study was conducted to evaluate the effects of ketamine, midazolam, and nitrous oxide anesthesia (K-M) in dogs artificially ventilated with 66% nitrous oxide and 33% oxygen or 100% oxygen. These dogs were submitted to experimental cervical esophagoplasty. Sixteen clinically healtly mixed breed dogs with mean body weight of 14.2 ± 3.78kg were studied. A 12-hour fasting period was established for each dog. Anesthesia was produced with 10mg.kg-1 ketamine and 0.5mg.kg-1 midazolam administered intravenously. Anesthesia was maintained with 5mg.kg-1 and 0.25mg.kg-1 midazolam IV as a bolus injection every 10 minutes after induction. Two groups were studied: N2O and O2. In one group (N2O) 8 dogs were artificially ventilated with 66% nitrous oxide (N2O) and 33% oxygen (O2). In the other group (O2) 8 dogs were artificially ventilated with 100% O2. Both groups were submitted to an experimental cervical esophagoplasty. In order to compare both treatments heart rate, systolic, diastolic, and mean blood pressure, pulse oximetry and body temperature were recorded. Analgesia was compared between groups as the need of supplementary doses of K-M. The results demonstrated that K-M injectable anesthesia do not produce cardiovascular depressant effects and hypothermia, promotes quiet induction and satisfactory recovery with salivation and produces adequate analgesia and muscular relaxation to cervical esophagus in dogs. Additional doses of K-M were necessary (p<0.05) in the O2 group suggesting that nitrous oxide decreases the dose of K-M in dogs.
ketamine; midazolam; nitrous oxide; dogs
