title: Cerebral and brainstem electrophysiologic activity during euthanasia with pentobarbital sodium in horses.
abstract: BACKGROUND
  An overdose of pentobarbital sodium administered i.v. is the most commonly used method of euthanasia in veterinary medicine. Determining death after the infusion relies on the observation of physical variables. However, it is unknown when cortical electrical activity and brainstem function are lost in a sequence of events before death.
  
  
  OBJECTIVE
  To examine changes in the electrical activity of the cerebral cortex and brainstem during an overdose of pentobarbital sodium solution for euthanasia. Our testing hypothesis is that isoelectric pattern of the brain in support of brain death occurs before absence of electrocardiogram (ECG) activity.
  
  
  METHODS
  Fifteen horses requiring euthanasia.
  
  
  METHODS
  Prospective observational study. Horses with neurologic, orthopedic, and cardiac illnesses were selected and instrumented for recording of electroencephalogram, electrooculogram, brainstem auditory evoked response (BAER), and ECG. Physical and neurologic (brainstem reflexes) variables were monitored.
  
  
  RESULTS
  Loss of cortical electrical activity occurred during or within 52 seconds after the infusion of euthanasia solution. Cessation of brainstem function as evidenced by a lack of brainstem reflexes and disappearance of the BAER happened subsequently. Despite undetectable heart sounds, palpable arterial pulse, and mean arterial pressure, recordable ECG was the last variable to be lost after the infusion (5.5-16 minutes after end of the infusion).
  
  
  CONCLUSIONS
  Overdose of pentobarbital sodium solution administered i.v. is an effective, fast, and humane method of euthanasia. Brain death occurs within 73-261 seconds of the infusion. Although absence of ECG activity takes longer to occur, brain death has already occurred.
authors: Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, 95616.
authors: M
authors: M
authors: Aleman
authors: D C
authors: DC
authors: Williams
authors: A
authors: A
authors: Guedes
authors: J E
authors: JE
authors: Madigan
mesh_terms: D000818:Animals; D001794:Blood Pressure; D001933:Brain Stem / Q000187:drug effects* / Q000502:physiology; D054022:Cerebrum / Q000187:drug effects* / Q000502:physiology; D004569:Electroencephalography / Q000662:veterinary*; D037901:Euthanasia, Animal / Q000379:methods*; D005260:Female; D006736:Horses / Q000502:physiology*; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010424:Pentobarbital / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D006993:Hypnotics and Sedatives; D010424:Pentobarbital
keywords: Brainstem auditory evoked response; Death; Electroencephalogram; Equine