Eye temperature and heart rate variability of calves disbudded with or without local anaesthetic

TitleEye temperature and heart rate variability of calves disbudded with or without local anaesthetic
Publication TypeJournal Article
Year of Publication2008
AuthorsStewart, M., Stafford K.J., Dowling S.K., Schaefer A.L., and Webster J.R.
JournalPhysiology and Behavior
Volume93
Issue4-5
Pagination789 - 797
Date Published2008
ISBN Number00319384 (ISSN)
KeywordsACTH, Adrenocorticotropic Hormone, analysis of variance, Anesthesia, Local, animal behavior, animal experiment, Animals, article, Behavior, body temperature, calf (bovine), cattle, controlled study, eye, Eye temperature, heart rate, Heart rate variability, hydrocortisone, hypothalamus hypophysis system, Infrared thermography, local anesthesia, nonhuman, priority journal, Temperature, thermography
Abstract

The possibility that pain can be detected from changes in eye temperature and heart rate variability (HRV) during disbudding was examined in thirty calves, randomly assigned to four treatments: 1) sham handling (control), 2) local anaesthetic (LA, cornual nerve injection) and sham disbudded, 3) sham LA and disbudded, 4) LA and disbudded. During a 40 min sampling period, maximum eye temperature, behavior and HRV parameters were recorded continuously. One week later, twelve disbudded calves were injected with adrenocorticotrophic hormone (ACTH) or saline and maximum eye temperature was recorded. There was a rapid drop in eye temperature during the 5 min following disbudding without LA (P < 0.05). Eye temperature then increased and was higher than baseline over the remaining sampling period following both disbudding procedures (P < 0.001), a response which could not be explained by increased physical activity LA increased eye temperature prior to disbudding (P < 0.001). Heart rate increased (P < 0.001) during the 5 min following disbudding with and without LA, however, LF/HF ratio only increased during this time (P < 0.01) following disbudding without LA. Eye temperature did not change following ACTH, suggesting that hypothalamus-pituitary-adrenal axis (HPA) activity is not responsible for the changes in eye temperature following disbudding. The increase in LF/HF ratio following disbudding without LA suggests an acute sympathetic response to pain, which could be responsible for the drop in eye temperature via vasoconstriction. HRV and eye temperature together may be a useful non-invasive and more immediate index of pain than HPA activity alone. © 2007 Elsevier Inc. All rights reserved.

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