American journal of veterinary research
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Comparative Study
Cardiopulmonary effects of enflurane and isoflurane in the dog.
The cardiopulmonary effects of 2 new inhalant anesthetics, enflurane and isoflurane, were studied in nonsedated, previously instrumented, awake dogs. Base line values were determined, and anesthesia was induced and maintained with the drug being studied. ⋯ The depression of cardiopulmonary function from both agents increased with increasing depth of anesthesia. Enflurance produced muslce twitching, but isoflurane did not.
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As a result of the continuing threat of Venezuelan equine encephalomyelitis (VEE), a study was made to determine if revaccination against VEE (TC-83 vaccine) was feasible and if revaccination could be incorporated into other routine vaccination practices. Of the horses given annual vaccination with bivalent western equine encephalomyelitis (WEE) and eastern equine encephalomyelitis (EEE) vaccine, 57% retained detectable serum-neutralizing (SN) antiboyd titers for VEE 18 months after the initial VEE vaccination was given. Of horses with no record of WEE-EEE vacinnation, 100% retained detectable VEE SN antibody titers over the same period. ⋯ This increase indicated that similar antigenic factors for VEE are possibly present in bivalent WEE-EEE vaccine. In horses previously vaccinated against WEE-EEE and VEE, the best SN antibody response to VEE revaccination occurred when VEE vaccine was given simultaneously with the bivalent WEE-EEE vaccine. Of 150 serum samples tested by both the SN and the hemagglutination-inhibiton tests, agreement between positive reactions at greater than or equal to 1:10 was 70% for VEE, 81% for EEE, and 87% for WEE.
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The cardiopulmonary effects of droperidol-fentanyl, nitrous oxide, and atropine were evaluated in 12 adult male Beagle dogs. All dogs were surgically instrumented with a cardiac output thermistor and arterial and venous catheters and were prepared with a chronic tracheostomy. Each dog was used as its own control, and data obtained when dogs were nonanesthetized and nonmedicated were compared with data recorded after the test drugs were administered. ⋯ Cardiovascular changes were not seen when nitrous oxide was added; however, analgesia and muscle relaxation were improved. Premedication with atropine sulfate resulted in increased cardiac output, heart rate, and diastolic pressure, and subsequent administration of droperidol-fentanyl with nitrous oxide caused a transient increase in mean arterial and systolic pressure. This last anesthetic regimen, along with assisted or controlled respiration, seems to provide an excellent anesthetic state with minimal cardiopulmonary depression.
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The neurally evoked contractile response of the upper lip muscles of horses anesthetized with halothane was used to evaluate the neuromuscular blocking property of oxytetracycline which was administered intravenously at total dose rate of 21 to 28 mg/kg. This dose rate did not alter the contractile response which had a mean control value (and standard error; SE) of 1.76 plus or minus 0.22 kg. Arterial blood pressure was not affected by these dose rates. ⋯ Moderate hypocalcemia induced by infusion of sodium oxalate did not enhance the neuromuscular blocking property of this antibiotic. Since the dose rates of the oxytetracycline preparation used had a small effect on calcium concentration of equine serum (smaller than 0.3 mg/dl), calcium binding does not seem to play a major role in the neuromuscular blocking effect of this antibiotic. It was concluded that the weak neuromuscular blocking effect of oxytetracycline is not a significant etiologic factor in the acute type of adverse reaction to this antibiotic that is occasionally encountered in horses.
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Ci 744 (20 mg/kg, given intramuscularly (IM) produced a reliable level of surgical anesthesia in both dogs and cats. Animals anesthetized in this way did not have an increased sensitivity to cardiac fibrillation after they were given epinephrine. Epinephrine-induced ventricular arrhythmia observed in C1 744-anesthetized animals was eliminated in cats and was markedly reduced in dogs by bilateral vagotomy. ⋯ Pentobarbital anesthesia, like C1 744 anesthesia, did not sensitize the heart, whereas a significant number of thiamylal-halothane-anesthetized animals died from cardiac fibrillation after they had been given epinephrine. Additional dogs were anesthetized with C1 744 or pentobarbital and given a series of pressor and depressor agents (isoproterenol, epinephrine, tyramine, 1, 1-dimethyl-4-phenylpiperazium iodide (DMPP) plus bilateral carotid occlusion) before and after vagotomy. The responses with either anesthetic were similar with the exception that the reflex bradycardia to pressor agents was more evident in C1 744- than in pentobarbital-anesthetized dogs.