Animal discomfort: A concept analysis using the domesticated pig (Sus scrofa) as a model

The term discomfort is frequently used in for example biomedical studies, animal experimentation for farming purposes, animal welfare legislation, and ethical permits for animal experimentation. However, the concept of “animal discomfort” still remains unclear. Using the domesticated pig as a model, we performed a Walker and Avant concept analysis to develop an operational definition of animal discomfort. A total of 2,594 documents published in English were retrieved from Scopus database. Among them, 118 were retained for analysis as they contained either: 1 - a definition and/or measurement of discomfort in animals, including pigs; 2 – definition and/or measurement of pain, suffering, or sickness in pigs only. The literature review showed that animal discomfort intersects on three domains: physical, physiological, and mental discomfort. The presence of discomfort leads to a sense of uneasiness that results in behaviorally visible consequences comprising animals’ attempts to avoid or alleviate the source(s) of this affective state. Accordingly, our proposed operational definition of animal discomfort is: short- or long-lived negative affective state featured by physical, physiological and/or mental components, induced by internal or external stimuli, ranging from mild to severe, potentially occurring together with other negative affective states, and leading to avoidance or attempt to alleviate the source of uneasiness. Access to a shared definition of this central concept in animal welfare may be one initial step to facilitate legislation consistency, improve animal research integrity, and ultimately promote a more sustainable livestock production.