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

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.