Validation of the acute electroencephalographic responses of calves to noxious stimulus with scoop dehorning.
OBJECTIVE
To validate use of the electroencephalogram (EEG) and a minimal anaesthesia model for assessment of noxious sensory input caused by scoop dehorning of calves.


METHODS
Twenty Friesian heifers weighing 125-178 kg were maintained under light general anaesthesia using halothane and an established protocol (minimal anaesthesia model). They were then dehorned using a scoop dehorner either with (DH+LA) or without (DH) a lignocaine ring block, and changes in the EEG and electrocardiogram (ECG) recorded. Median frequency (F50), 95% spectral edge frequency (F95) and total power (Ptot) were derived from the EEG data.


RESULTS
There were significant increases in the F50 (p<0.01) and F95 (p<0.01), and a decrease in Ptot (p<0.01) following dehorning in the DH group, but there were no changes in the DH+LA group. Transient bradycardia in the first 75 sec following dehorning was recorded in the DH group compared with both pre-treatment values in the same group and with the DH+LA group (p<0.001). Tachycardia was evident by 15 min after dehorning in the DH but not the DH+LA group.


CONCLUSIONS
The results validate use of the EEG and a minimal anaesthesia model for assessment of noxious sensory inputs in cattle.
Animal Welfare Science and Bioethics Centre, Massey University, Private Bag 11222, Palmerston North, New Zealand. t.g.gibson@massey.ac.nz
T J
TJ
Gibson
C B
CB
Johnson
K J
KJ
Stafford
S L
SL
Mitchinson
D J
DJ
Mellor
D000768:Anesthesia, General / Q000662:veterinary*; D000779:Anesthetics, Local / Q000008:administration & dosage; D000818:Animals; D002417:Cattle / Q000502:physiology / Q000601:surgery; D002425:Cautery / Q000379:methods / Q000662:veterinary; D004562:Electrocardiography / Q000379:methods / Q000662:veterinary; D004569:Electroencephalography / Q000379:methods / Q000592:standards / Q000662:veterinary*; D005260:Female; D006733:Horns / Q000601:surgery*; D008012:Lidocaine / Q000008:administration & dosage; D010147:Pain Measurement / Q000379:methods / Q000592:standards / Q000662:veterinary*; D013610:Tachycardia / Q000453:epidemiology / Q000662:veterinary
D000779:Anesthetics, Local; D008012:Lidocaine