American journal of veterinary research
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Comparative Study
Arterialized capillary blood used to determine the acid-base and blood gas status of dogs.
Blood samples were collected by microhematocrit tube from posterior medial margin of the shaved, but otherwise untreated, canine ear. Acid-base and blood gas values of these samples were compared with the values of samples obtained simultaneously from the carotid artery. ⋯ Once a week determinations of acid-base and blood gas status with such arterialized capillary blood from a group of awake dogs showed within-subject variance to be significantly less (P less than 0.05) than between-subject variance; thus, uniqueness of individual dogs was reliably revealed. This technique also was used to demonstrated breed differences for acid-base and blood gas characteristics.
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Constantly coupled ventricular bigeminy in dogs can be elicited by intravenous boluses of thiamylal sodium. Properties of the bigeminal rhythm are similar to those produced by halothane or cyclopropane inhalation anesthetic-epinephrine-induced dysrhythmias. ⋯ Atropine was effective in abolishing ventricular bigeminy in most cases through overdrive suppression. Propranolol appeared to abolish ventricular bigeminal rhythms by suppression of sympathetic efferent activity without causing noticeable changes in arterial blood pressure.
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Comparative Study
Enflurane, halothane, and isoflurane potency in horses.
The minimal alveolar concentration of anesthetic required to prevent gross purposeful movement in response to electrical stimulation of oral mucous membranes was determined in horses for 3 agents. Equipotent concentrations of enflurane were 2.12 volumes %; of halothane, 0.88 volumes %; and of isoflurane, 1.31 volumes +. ⋯ From these data and the minimal alveolar concentration information, anesthetic indices were determined for each agent. The indices for enflurane, halothane, and isoflurane were 2.26, 2.60, and 2.33, respectively.
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The cardiovascular effects of gallamine triethiodide and succinylcholine chloride were studied in Beagle dogs during controlled halothane anesthesia. Small but significant increases in heart rate and mean arterial presssure were observed 1 minute after intravenous injection of succinylcholine chloride. Intravenous injection of gallamine triethiodide did not produce significant cardiovascular changes.
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The cardiopulmonary effects resulting from the combination of xylazine and ketamine hydrochloride were evaluated in the adult horse. Xylazine (1.1 mg mg/kg) administered intravenously prior to or simultaneously with ketamine hydrochloride (2.2 mg/kg; intravenous) provided excellent analgesia and light anesthesia in all horses. Cardiac output, arterial blood pressure, pulmonary arterial pressure, central venous pressure, and pulmonary arterial wedge pressure remained within normal limits for the adult horse. ⋯ In the horse, larger dosages of ketamine hydrochloride (6.6 mg/kg) following sedation with xylazine (1.1 mg/kg; intravenous) were accompanied by muscular tremor and rigidity, mydriasis, oculogyric movements, sweating, hypertension, tachycardia, and increased rectal temperature during recovery from anesthesia. Providing there is good sedation from xylazine, the combination of xylazine and ketamine hydrochloride as a short-term intravenous anesthetic technique in the horse appears safe and acceptable providing reasonably stable cardiopulmonary function. If the sedative properties of xylazine are not apparent or if excessive dosages of ketamine hydrochloride are used, the drug combination results in serious side effects precluding its use for anesthesia in the horse.