title: Electroencephalogram of Healthy Horses During Inhaled Anesthesia.
abstract: BACKGROUND
  Previous study of the diagnostic validity of electroencephalography (EEG) to detect abnormalities in equine cerebral cortical function relied on the administration of various drugs for sedation, induction, and maintenance of general anesthesia but used identical criteria to interpret recordings.
  
  
  OBJECTIVE
  To determine the effects of 2 inhalation anesthetics on the EEG of healthy horses.
  
  
  METHODS
  Six healthy horses.
  
  
  METHODS
  Prospective study. After the sole administration of one of either isoflurane or halothane at 1.2, 1.4, and 1.6 times the minimum alveolar concentration, EEG was recorded during controlled ventilation, spontaneous ventilation, and nerve stimulation.
  
  
  RESULTS
  Burst suppression was observed with isoflurane, along with EEG events that resembled epileptiform discharges. Halothane results were variable between horses, with epileptiform-like discharges and bursts of theta, alpha, and beta recorded intermittently. One horse died and 2 were euthanized as the result of anesthesia-related complications.
  
  
  CONCLUSIONS
  The results of this study indicate that the effects of halothane and isoflurane on EEG activity in the normal horse can be quite variable, even when used in the absence of other drugs. It is recommended that equine EEG be performed without the use of these inhalation anesthetics and that general anesthesia be induced and maintained by other contemporary means.
authors.affiliation: William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA.
authors.forename: D C
authors.initials: DC
authors.lastname: Williams
authors.affiliation: Departments of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA.
authors.forename: M R
authors.initials: MR
authors.lastname: Aleman
authors.affiliation: Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Brosnan
authors.affiliation: Section of Emergency and Critical Care, Cornell University, Ithaca, NY.
authors.forename: D J
authors.initials: DJ
authors.lastname: Fletcher
authors.forename: T A
authors.initials: TA
authors.lastname: Holliday
authors.affiliation: Department of Neurology, University of California Davis Medical Center, Sacramento, CA.
authors.forename: B
authors.initials: B
authors.lastname: Tharp
authors.affiliation: Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA.
authors.forename: P H
authors.initials: PH
authors.lastname: Kass
authors.affiliation: Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA.
authors.forename: E P
authors.initials: EP
authors.lastname: Steffey
authors.affiliation: Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA.
authors.forename: R A
authors.initials: RA
authors.lastname: LeCouteur
mesh_terms: D000769:Anesthesia, Inhalation / Q000662:veterinary*; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D018592:Cross-Over Studies; D004569:Electroencephalography / Q000187:drug effects / Q000662:veterinary*; D006221:Halothane / Q000494:pharmacology*; D006736:Horses / Q000601:surgery*; D007530:Isoflurane / Q000494:pharmacology*; D015203:Reproducibility of Results
chemical_list: D018685:Anesthetics, Inhalation; D007530:Isoflurane; D006221:Halothane
keywords: Epilepsy; Equine; Halothane; Isoflurane; Seizures