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Assessment of the affective component of pain in dairy calves

University of British Columbia

Whether they live in our homes, farms or laboratories, many animals are subjected to painful procedures. In humans, pain assessment is mostly done through verbal self report, but the assessment of pain in non-verbal humans and animals remains a challenging task. Pain can be divided in two main components: a reflex response, and an emotional experience. The focus of pain research has largely been centered around reflex responses when animals (and human neonates until recently) are the ones subjected to pain. The aim of this thesis was to address this gap by developing a method to assess the emotional experience (or ‘affective state’) that dairy calves go through during painful procedures. To do so, the focus of our novel approach was on how animals formed memories of procedures they were subjected to. In the first chapter, I reviewed the literature on the assessment of emotion in dairy cattle. I highlighted that many measures reflect how aroused animals are rather than whether they are in a positive or negative state (valence), but that measures based on cognition were promising in evaluating valence. In the second chapter, I studied the pain caused by different injection methods by looking at how much milk calves were willing to give up to avoid injections. Although all methods were more aversive than not receiving an injection, intramuscular injections were more aversive than subcutaneous or intranasal. In the third, fourth and fifth chapter, I studied how calves remembered different methods of disbudding (a procedure that prevents horn growth) by looking at how much they would avoid the place where they experienced the procedure. I found that calves remember disbudding as negative and that learned aversion is reduced if calves are provided pain control both during and after the procedure. In summary, calves showed not to be limited to a ‘knee-jerk’ response to pain. Rather, they formed impactful memories that affected their future behaviour, exhibiting complex emotional processing of pain.

Text

2020-11-26

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/76598

Applied Animal Biology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/