Validation of the acute electroencephalographic responses of calves to noxious stimulus with scoop dehorning

Author： Gibson TJ Johnson CB Stafford KJ Mitchinson SL Mellor DJ

ISSN： 1176-0710

Source： New Zealand Veterinary Journal, Vol.55, Iss.4, 2007-08, pp. : 152-157

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Abstract

AIM: 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 signifi cant 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.