This study provides baseline information on the potential use of propofol as a general anesthetic for horses. Using a Latin square design, propofol (2, 4, and 8 mg/kg) was administered intravenously on three separate occasions to six mature horses. Information about anesthetic induction, duration, and recovery was recorded along with results of rectal temperature, heart rate, respiratory rate, pHa, PaCO2 and PaO2. Statistical analysis included a mixed model analysis of variance, a general linear model analysis and least square means test for post hoc comparisons. A P < .05 was considered significant. The quality of induction of anesthesia varied from poor to good. Two horses were not recumbent following the lowest dose of propofol. Brief paddling limb movements occurred occasionally and unpredictably after recumbency induced by all three doses. During recovery, horses were uniformly calm and coordinated in their moves to stand. Duration of recumbency (minutes) was dose related; 15.05 +/- 1.58 (mean +/- SD) following 2 mg/kg, 31.06 +/- 5.56 following 4 mg/kg, and 47.85 +/- 13.63 following 8 mg/kg. During recumbency at all doses, heart rate significantly increased from a predrug value of 40 +/- 6 beats per minute. Substantial respiratory depression, characterized by a significant decrease in respiratory rate (from 11.7 +/- 2.9 to 3.7 +/- 1.6 breaths per minute) and increased PaCO2 (from 44.5 +/- 2.5 to 52.7 +/- 8.0 mm Hg) was seen only after 8 mg/kg. A significant decrease in PaO2 was observed throughout the recumbency induced by 8 mg/kg, and also at 3 and 5 minutes following induction of anesthesia with 4 mg/kg propofol.(ABSTRACT TRUNCATED AT 250 WORDS)

Background: The influence of sleep on the equine electroencephalogram (EEG) has not been well documented. Hypothesis: The objectives were to develop a noninvasive method of electrode placement for recording the EEG in horses and to establish normal EEG parameters for the various states of vigilance. Findings are compared with previously published reports on equine sleep based on electrocorticography (ECoG).Animals: Five neurologically normal horses. Methods: Overnight EEGs were recorded digitally in association with simultaneous videotaping of the horses' behavior. Data were analyzed by visual inspection, states of vigilance were identified, and representative segments were quantitatively processed. Transient EEG events were examined.Results: Slow wave sleep (SWS) was significantly different (P o .05) in frequency and power from drowsiness and rapid eye movement (REM) sleep. Second-degree heart block was associated with SWS as were transient events commonly recognized in EEGs of humans. Drowsiness and REM sleep were similar. In both, background activity was low-amplitude b activity admixed with prominent activity of approximately 4 Hz. Standing REM sleep was associated with numerous partial collapses in 1 horse.Conclusions and Clinical Importance: Normative data for several states were described and probable benign variants identified. This information will serve as control data for sedative and anesthetic studies in this species. The sleep patterns observed during this study are those of horses removed from their usual surroundings, and thus may represent those encountered in a clinical environment.

For regional perfusion of the tarsus, IV infusion is preferred to intraosseous infusion, because higher concentrations are achieved in the synovial fluid, and the procedure is easier to perform.

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In monkeys, dogs and swine (six each) we tested the reduction of the isoflurane MAC (minimal alveolar concentration) produced by 2 mg.kg-1 morphine intravenously (i.v.) and the concurrent effect on PCO2 with spontaneous ventilation. MAC fell to a minimum of 55% of control at 53 min in monkeys, 50% at 38 min in dogs and 13% at 33 min in swine. PaCO2 rose at constant MAC with morphine to 55-60 mmHg, but did not fall over the next several hours despite the decline of plasma morphine concentration, and the resulting needed rise in isoflurane concentration to keep the anaesthesia depth at 1 MAC. After isoflurane concentration had returned to pre-morphine control levels, naloxone immediately reduced PaCO2 to or below control level. Morphine pharmacokinetics in the three species studied conformed to a two-compartment model.