American journal of veterinary research
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Succinylcholine is a depolarizing neuromuscular blocking drug, which is rapidly hydrolyzed by the enzyme pseudocholinesterase. In Greyhounds, the metabolism of certain drugs is atypical relative to other breeds, and it has been suggested that Greyhounds may be an atypical population, with lower pseudocholinesterase activity, slower hydrolysis of the drug succinylcholine, and a prolonged duration of action of the drug, compared with a mixed-breed control population. Six healthy adult Greyhounds and 6 healthy adult mixed-breed dogs were studied. ⋯ Subsequent doses were administered after complete recovery. The time to 50% recovery after succinylcholine administration in Greyhounds (38 minutes, dose 1, single twitch) was not significantly different than the time to 50% recovery in mixed-breed dogs (29 minutes, dose 1, single twitch), using either monitoring technique. Pseudocholinesterase activity was also not significantly different between the Greyhounds (1,685 mU/ml) and the mixed-breed dogs (1,588 mU/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
Comparison of several combinations for anesthesia in rabbits.
Few safe and effective anesthesia regimens have been described for use in rabbits, partially because of the susceptibility of this species to sometimes fatal respiratory depression. Although inhalant anesthetics are generally safer than injectable anesthetics, their use may be limited by lack of equipment or facilities. This study was conducted to compare effects of several injectable anesthetics in rabbits on response to noxious stimuli, heart rate, respiratory rate, and rectal temperature. ⋯ The combination that induced the longest duration of anesthesia was XAK. It was concluded that XAK was preferable for longer periods of anesthesia (60 to 120 minutes), although it induces severe hypothermia. For short periods of anesthesia, xylazine-pentobarbital, xylazine-EMTU, or ketamine-xylazine were deemed adequate; however, xylazine-EMTU induced the best survivability and consistency.
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Evoked potentials were induced by transcranial stimulation and recovered from the spinal cord, and the radial and sciatic nerves in six dogs. Stimulation was accomplished with an anode placed on the skin over the area of the motor cortex. Evoked potentials were recovered from the thoracic and lumbar spinal cord by electrodes placed transcutaneously in the ligamentum flavum. ⋯ Conduction velocities were estimated from wave latencies and distance traveled. The technique allowed recovery of evoked potentials that had similar characteristics among all dogs. Conduction velocities of potentials recovered from the radial and sciatic nerves suggested stimulation of motor pathways; however, the exact origin and pathway of these waves is unknown.
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Midazolam HCl (1.0 or 2.0 mg/kg of body weight) was administered IM to 6 Canada geese to determine a sedative dose that would allow positioning for radiologic examination. The effects of both test doses on cardiopulmonary function were evaluated at 5, 10, 15, 20, 30, and 40 minutes after drug administration and were compared with 2 end-tidal isoflurane concentrations (1.5 and 2.5%). The 2.0 mg/kg dosage induced moderate sedation at 15 and 20 minutes; sedation was adequate for positioning the geese. ⋯ Respiratory rate increased significantly (P less than 0.05) at 10, 15, 20, and 30 minutes with the 2.0 mg/kg dosage, and at 15 and 20 minutes with the 1.0 mg/kg dosage. Blood pressure and respiratory rate were significantly (P less than 0.05) decreased with isoflurane when compared with baseline data and the midazolam test doses. The results of this study indicate that midazolam at a dosage of 2.0 mg/kg induces adequate sedation with minimal cardiopulmonary changes, and, as an alternative to general anesthesia with isoflurane, provides a satisfactory level of restraint for radiography.
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Plasma cortisol concentrations were compared in canine surgical patients given etomidate (2 mg/kg of body weight, IV) or thiopental sodium (12 mg/kg, IV) for anesthetic induction. Blood samples to determine plasma concentrations of etomidate were obtained at 0, 5, 10, 15, and 30 minutes and 1, 2, 3, 4, 5, 6, 8, 12, and 24 hours after induction. Adrenocortical function was evaluated before surgery by use of adrenocorticotropic hormone stimulation tests. ⋯ Plasma cortisol concentrations did not correlate with plasma etomidate concentrations. We conclude that, compared with thiopental, a single bolus injection of etomidate reduces the adrenocortical response to anesthesia and surgery from 2 to 6 hours after induction. Because cortisol concentrations were significantly higher than baseline, and because cardiopulmonary function is maintained after a single bolus injection of etomidate, it can be considered a safe induction agent in dogs.