Validation of behavioural indicators used to assess unconsciousness in sheep

M.T.W. Verhoeven*, M.A. Gerritzen, M. Kluivers-Poodt, L.J. Hellebrekers, B. Kemp

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

20 Citations (Scopus)


The validity of behavioural indicators to assess unconsciousness under different slaughter conditions is under (inter)national debate. The aim of this study was to validate eyelid-, withdrawal-, threat reflex and rhythmic breathing as indicators to assess unconsciousness in sheep. Sheep were monitored during repeated propofol anaesthesia (n = 12) and during non-stunned slaughter (n = 22). Changes in the EEG and behavioural indices of consciousness/unconsciousness were assessed and compared in sheep. Threat reflex and rhythmic breathing correlated with EEG activity during propofol anaesthesia whilst absence of non-rhythmic breathing or threat reflex indicated unconsciousness. None of the behavioural indicators correlated with EEG activity during non-stunned slaughter. Absence of regular breathing and eyelid reflex was observed 00:27 ± 00:12 min and 00:59 ± 00:17 min (mean ± SD) respectively after animals were considered unconscious, indicating that absence of regular breathing and eyelid reflex are distinctly conservative indicators of unconsciousness during non-stunned slaughter in sheep.
Original languageEnglish
Pages (from-to)144-153
JournalResearch in Veterinary Science
Publication statusPublished - 2015


  • spectral edge frequency
  • halothane-anesthetized calves
  • ventral-neck incision
  • electroencephalographic responses
  • bispectral index
  • broiler-chickens
  • slaughter
  • pigs
  • anesthesia
  • consciousness


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