Abstract
Pain in animals is typically assessed using reflexive and physiological responses. These measures allow inferences regarding nociception but provide little basis for conclusions about the affective component of pain (i.e. how negatively the experience is perceived). Calves routinely undergo painful procedures on commercial farms, including hot-iron disbudding, providing a convenient model to study pain in animals. The aim of this study was to investigate the affective component of post-procedural pain due to hot-iron disbudding, using conditioned place aversion. Calves (n = 31) were subjected to two procedures (one bud at a time): one without post-procedural pain control and the other with the use of a nonsteroidal anti-inflammatory drug (either meloxicam (n = 16) or ketoprofen (n = 15)). All procedures included the use of local anaesthesia (lidocaine). Place conditioning was tested 2 days after the last treatment by allowing calves to freely roam between the pens where they had previously been disbudded. Calves spent more time, and lay down more frequently, in the pen where they received meloxicam compared with the pen where they only received a local block. Surprisingly, calves avoided the pen where they received ketoprofen compared with the control treatment pen. We hypothesize that the shorter duration of action of ketoprofen resulted in increasing pain at the end of the conditioning period, explaining the increased aversion to this treatment. These results illustrate the value of place conditioning paradigms to assess the affective component of pain in animals, and suggest that the animal's evaluation of painful events depends upon the time course of when the pain is experienced.
Highlights
Many approaches to study animal pain can be found in the literature, most of which rely on either nociceptive processes, activation of the hypothalamic–pituitary–adrenal axis or indirect measures of activation of the sympathetic nervous system
Three calves were excluded from the study: two for not fulfilling pre-exposure criteria and one for falling sick between the first and second treatment, which resulted in 16 calves in the meloxicam group and 15 in the ketoprofen group
Time spent in the pen was not affected by test session number, order of treatment, colour of treatment pen and side of the first bud disbudded (t1,152 = 0.4, p = 0.7; t1,26 = 0.6, p = 0.5; t1,26 = 0.5, p = 0.6; t1,26 = −0.3, p = 0.8, respectively) but there was an interaction between treatment received in the pen (Control or nonsteroidal anti-inflammatory drug (NSAID)) and the NSAID used (t1,152 = 4.4, p < 0.001)
Summary
Many approaches to study animal pain can be found in the literature, most of which rely on either nociceptive processes (e.g. hypersensitivity of injured areas [1]), activation of the hypothalamic–pituitary–adrenal axis (e.g. salivary concentration of cortisol [2]) or indirect measures of activation of the sympathetic nervous system (e.g. heart rate [3]). Such responses reflect the sensory component of pain and do not require processing by the central nervous system.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
