UBC Theses and Dissertations
Cognitive bias as a method of pain assessment following hot-iron dehorning of dairy calves Neave, Heather Whittaker
Pain is one of the most highly studied emotions in animals, and the interaction between pain and cognitive processes is well documented in humans. Recent research has attempted to use changes in cognitive processes as a method of assessing emotions of animals. This approach is based on the influence of mood states on attention to and interpretation of information. Studies with humans have shown that depressed or anxious people interpret ambiguous stimuli more negatively, while people in positive states have more optimistic interpretations. These judgement bias tasks have been applied in different animal species, but none have investigated how pain affects emotional states. Here I present the first report of cognitive bias in cattle and the first evidence of a bias in response to pain in any non-human species. I assessed cognitive bias in dairy calves before and after hot-iron dehorning. Previous work has shown that calves experience pain for at least 24 h after this procedure. Calves (n=17) were trained in a go/no-go task to expect positive (milk reward) or negative (time-out with no opportunity to access milk) outcomes following nose contact with a video screen that was either white or red; calves were alternatively assigned white or red as the positive training stimulus, and the opposite colour as the negative training stimulus. Once calves had learned to discriminate between these two training stimuli, they were tested with unreinforced ambiguous probes (screen colours at 25%, 50%, and 75% red) introduced randomly within training sessions. Probes were presented in sessions 1 d before and 1 d after dehorning. Calves approached the ambiguous probe screens less frequently after dehorning (88±5, 55±5, 11±5 % for the near-positive probe, the halfway probe, and the near-negative probe, respectively) compared to before dehorning (92±5, 68±5, 23±5 %), a difference that was numerically most pronounced for the halfway and near-negative probes. These results indicate that calves experiencing pain during the hours after hot-iron dehorning exhibit a negative "pessimistic" bias and support the use of judgement bias tasks in the assessment of animal emotions.
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Attribution-NonCommercial-NoDerivs 2.5 Canada