Analgesia and behavioral responses of dogs given oxymorphone-acepromazine and meperidine-acepromazine after methoxyflurane and halothane anesthesia.

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.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose response to butorphanol administered subcutaneously to increase visceral nociceptive threshold in dogs.

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.

Dose-response of intravenous butorphanol to increase visceral nociceptive threshold in dogs.

This study was designed to determine the effective analgesic dose of butorphanol administered intravenously to obtund visceral nociception, as well as to determine duration of this effect. Additionally, cardiovascular changes and sedative effects were defined. Eight healthy dogs were each given five doses of butorphanol (0.025, 0.05, 0.1, 0.2, and 0.4 mg/kg) plus a sterile water placebo intravenously in a randomized blinded format. Antinociception was assessed using an inflatable Silastic balloon inserted into the colon. Blood pressures and pulse rates were measured with a noninvasive monitor. The greatest efficacy and longest duration of antinociception were produced by 0.4 mg/kg of butorphanol, with a duration of 38 +/- 9 min. Arterial blood pressure and pulse rate did not vary at antinociceptive doses. Mild sedation was observed at all doses, which generally lasted longer than the antinociceptive effects. These data suggest that butorphanol can be given alone intravenously to provide visceral antinociception lasting 30-45 min without significant side effects.

Comparison of direct and indirect blood pressure measurement in anesthetized dogs.

This study was conducted to determine whether blood pressures and pulse rate could be determined accurately by indirect measurements from the front and hind legs of 15- to 40-kg dogs anesthetized with isoflurane. Indirect measurements from each animal were compared to direct measurements obtained from a catheter placed into the abdominal aorta via the femoral artery at four ranges of systolic pressure. When systolic pressure was above 80 mm Hg, indirect measurements were either the same as direct measurements or slightly lower. However, when systolic pressures were below 80 mm Hg, indirect systolic pressure measurements were 6 to 15% higher than direct measurements. Larger differences in diastolic pressures were found, which resulted in differences in mean pressure. The most accurate measurements were found when the cuff width-to-limb circumference ratio was between 0.4 and 0.6 and when systolic pressure was between 80 and 100 mm Hg.