Abstract
Objective
To investigate whether induction of the ultraviolet B and heat rekindling (UVB/HR)
model alters burrowing behaviour in rats.
Study design
Randomized, blinded, prospective experimental study.
Animals
Sixteen adult male Wistar rats weighing 250–300 g.
Methods
In the UVB/HR group (n = 8), UV irradiation was delivered to the heel area of the right plantar pelvic limb
paw at a dose of 1000 mJ cm−2, using a narrow-band UVB light source. Twenty-four hours later, heat rekindling was
performed by placement of a feedback-controlled thermode set at a constant temperature
of 45 °C over the area of UVB irradiation for 5 minutes. Both interventions were carried
out under pentobarbital anaesthesia. The ‘sham’ group (n = 8) was anaesthetized only. In the burrowing test, rats were housed singly for 2
hours in cages furnished with a burrow filled with sand. The amount of sand remaining
in the burrow after 2 hours was weighed and the amount displaced from the burrow calculated.
The burrowing test was carried out for two consecutive days prior to UVB irradiation
(day 0), on day 1 prior to HR, on days 2 and 3 after UVB exposure and at equivalent
time points in the sham group.
Results
Rats in the sham group burrowed means (SD) of 2429 (73) g and 2358 (124) g of sand
on days −2 and 3, respectively, while those in the UVB/HR group burrowed 2460 (26)
and 2419 (58) g on days −2 and 3, respectively. There was no significant effect of
treatment on the amount of sand burrowed at any time point.
Conclusions and clinical relevance
Pain associated with UVB/HR model induction is below the threshold required to affect
rat burrowing behaviour and therefore questions the face validity of UVB/HR as a translational
model of inflammatory pain.
Keywords
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Article info
Publication history
Accepted:
November 24,
2015
Received:
August 5,
2015
Identification
Copyright
© 2016 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Inc. All rights reserved.
