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To compare mask anesthesia induction and recovery characteristics between 2 inhalant anesthetic agents: isoflurane and sevoflurane.


16 clinically normal, young adult Beagles.


Using a cross-over design, dogs were randomly selected to receive sevoflurane or isoflurane via a face mask and a circle anesthetic system. Vaporizer setting concentrations were increased in step-wise, equal minimum alveolar concentrations (MAC) for each anesthetic until the vaporizer setting of 2.6% for isoflurane or 4.8% for sevoflurane (2 MAC) was reached. Concentration was kept constant until the dog had a negative tail clamp response and was intubated. End-tidal concentration was maintained at 1.8 to 2.0% or 3.3 to 3.8% for isoflurane or sevoflurane, respectively (1.4 to 1.6 MAC) for 30 minutes. Dogs were allowed to recover with only tail clamp stimulation until a positive response was obtained. Extubation was performed when a spontaneous swallow reflex was observed. Dogs were allowed to achieve sternal recumbency and stand unassisted without further stimulation.


Sevoflurane induction resulted in shorter time to loss of palpebral reflex, negative tail clamp response, and time to tracheal intubation, and was of better quality than isoflurane induction. Both anesthetics were associated with rapid and smooth recovery.


Sevoflurane mask induction is faster and of better quality, compared with isoflurane, in adult dogs. Recovery time and quality are comparable.

Clinical Relevance

On the basis of these results, sevoflurane is a suitable inhalant anesthetic for mask induction and recovery in adult dogs and appears to have some advantages over isoflurane, including faster and smoother mask induction. (Am J Vet Res 1998;59:478–481)

Free access
in American Journal of Veterinary Research


This study was designed to test analgesia, duration, and cardiovascular changes induced by meperidine (mep) and oxymorphone (oxy) following methoxyflurane (mof) and halothane (hal) anesthesia. Eight healthy dogs were given atropine and acepromazine, and anesthesia was induced with thiamylal and maintained with 1.5 minimal alveolar concentration of mof or hal for 1 hour during controlled ventilation. Eight treatments were given with each anesthetic: 3 with mep (0.5, 1.0, and 2.0 mg/kg, iv), 3 with oxymorphone (oxy; 0.05, 0.1, and 0.2 mg/kg, iv), and 2 placebos with sterile water. Test drugs were given at the end of anesthesia when early signs of recovery were evident. Minimal threshold stimulus/response nociception was assessed by use of an inflatable soft plastic colonic balloon. Blood pressures and pulse rate were measured with a noninvasive monitor. Meperidine and oxy were found to be effective analgesics and could be reversed with naloxone. Intravenous administration of 2.0 mg of mep/kg provided analgesia for 36 ± 6 minutes and 39 ± 15 minutes after mof and hal, respectively. In contrast, oxy was effective at all 3 doses with effects of iv administration of 0.2 mg of oxy/kg lasting 154 ± 13 minutes and 152 ± 12 minutes, after mof and hal, respectively. Analgesia could not be demonstrated after anesthesia for acepromazine, mof, or hal. Blood pressure was not changed by either anesthetic nor was it influenced by mep or oxy. Pulse rate was significantly depressed by the higher doses of oxy following hal, but was not changed by mep following either anesthetic. This study demonstrated the longer duration of analgesia of oxy. In addition, we could not find that analgesia was provided by either mof or hal following recovery from anesthesia.

Free access
in American Journal of Veterinary Research


Butorphanol (0.025, 0.05, 0.1, 0.2, 0.4, and 0.8 mg/kg of body weight, and placebo) was given sc to 8 healthy unmedicated dogs to determine its efficacy for visceral analgesia, using a colonic balloon for minimal threshold nociceptor stimulation. Degree of sedation; systolic, diastolic, and mean arterial pressure; and pulse rate were recorded. The highest 3 dosages, 0.2, 0.4, and 0.8 mg/kg, were found to be most effective, with 0.8 mg/kg the only dosage that was significantly different from control responses at the 45-minute interval. Duration of analgesia ranged from 23 to 53 minutes for all 6 dosages and dosing durations were not significantly different from one another. Blood pressures did not change, but pulse rate was significantly decreased by 0.8 mg of butorphanol/kg. We concluded that butorphanol is an effective visceral analgesic of relatively short duration in the dog.

Free access
in American Journal of Veterinary Research