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

Authors: Stafford KJ, Mellor DJ, Mitchinson SL, Johnson CB, Gibson TJ
Publication: New Zealand Veterinary Journal, Volume 55, Issue 4, pp 152-157, Aug 2007
Publisher: Taylor and Francis

Animal type: Cattle, Livestock, Production animal, Ruminant
Subject Terms: Anaesthesia/analgesia/sedation, Animal remedies/veterinary medicines, Animal welfare, Circulatory system/haematology, Husbandry/husbandry procedures, Diagnostic procedures, Evidence/information based methods, Nervous system/neurology, Pain, Surgery
Article class: Scientific Article

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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 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.
KEY WORDS: Bradycardia, calves, dehorning, electroencephalogram, lignocaine ring block, minimal anaesthesia model, nociception, pain, tachycardia

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