Electroencephalographic and cardiovascular variables as nociceptive indicators in isoflurane-anaesthetized horses.
OBJECTIVE
To evaluate Fourier-transformed electroencephalographic (EEG) variables, mean arterial blood pressure (MAP) and pulse rate as nociceptive indicators in isoflurane-anaesthetized horses.


METHODS
Five standardbred and three Norwegian cold-blooded trotter stallions undergoing castration, aged 2-4 years, mass 378-538 kg.


METHODS
All horses received intravenous (IV) detomidine (10 microg kg(-1) IV) and butorphanol (0.01 mg kg(-1) IV). Additional detomidine (4 microg kg(-1) IV) was administered in the induction area. Anaesthesia was induced with ketamine (2.5 mg kg(-1) IV) and diazepam (40 microg kg(-1) IV), and maintained for 30 minutes with isoflurane (end-tidal concentration of 1.4%) vaporized in oxygen. The electroencephalogram, MAP and pulse rate were recorded for 15 minutes, beginning 5 minutes before skin incision. Differences between the mean values of recordings taken before, and during surgery were calculated and tested for significant differences using a two-sided Student's t-test.


RESULTS
A significant rise in MAP and a fall in pulse rate were found. No significant change was found in any EEG variable. CONCLUSION/CLINICAL relevance Of the variables evaluated, MAP seems to be the most sensitive and reliable indicator of nociception in isoflurane-anaesthetized horses.
Haga
Henning A
HA
Department of Companion Animal Clinical Sciences, The Norwegian School of Veterinary Science, Oslo. andreas.haga@veths.no
Dolvik
Nils I
NI
D000758:Anesthesia / Q000662:veterinary; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects; D002490:Central Nervous System / Q000187:drug effects; D004569:Electroencephalography / Q000662:veterinary; D006339:Heart Rate / Q000187:drug effects; D006736:Horses / Q000502:physiology* / Q000601:surgery; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D009919:Orchiectomy / Q000662:veterinary*; D010147:Pain Measurement / Q000662:veterinary
D018685:Anesthetics, Inhalation; D007530:Isoflurane