The effect of early burn injury on sensitivity to future painful stimuli in dairy heifers

• Published in: PloS one Vol. 15; no. 6; p. e0233711
• Main Authors: Adcock, Sarah J. J, Tucker, Cassandra B
• Format: Journal Article
• Language: English
• Published: San Francisco Public Library of Science 03.06.2020; Public Library of Science (PLoS)
• Subjects: Age; Analysis; Animal sciences; Animal welfare; Autonomic nervous system; Behavior; Biology and Life Sciences; Burns; Data collection; Heart rate; Heifers; Injection; Injuries; Medicine and Health Sciences; Neonates; Nervous system; Newborn infants; Nociception; Pain; People and Places; Physical Sciences; Physiological aspects; Physiology; Vaccines; Variability; Zoology; United States; United States > US; California
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0233711

Animals that experience painful procedures as neonates are more sensitive to pain later in life. We evaluated whether disbudding with a heated iron at 3 (n = 12), 35 (n = 9), or 56 (n = 20) d of age affected heifers' pain responses to vaccine injections at 11 mo of age. Heifers responded to the injection procedure with struggling and changes in eye temperature and heart rate variability compared to a sham procedure the day before, and still had a heightened response 6 d later, regardless of disbudding age. However, some heart rate variability indices suggested increased sympathetic dominance in heifers disbudded at 35 d, compared to the other 2 age groups, independent of the injection procedure. We also found that heifers disbudded at 3 or 35 d had a higher mean heart rate after the injection procedure compared to those disbudded at 56 d. We conclude that: (1) heifers find injections aversive; and (2) there is some evidence that disbudding age influences autonomic nervous system activity later in life.