Manifestations of chronic and acute stress in dogs

Abstract Poor housing conditions, harsh training sessions and uncontrollable or unpredictable social environments are examples of the situations that may lead to reduced welfare status in dogs. Individuals that suffer from poor welfare presumably experience stress and may consequently exhibit stress responses. In order to evaluate stress responses as potential indicators of poor welfare in dogs, we review studies dealing with dogs subjected to stressors. The reported stress responses are categorized as being behavioural, physiological or immunological, and demonstrate the various ways stress is manifested in the dog. Stressors such as noise, immobilization, training, novelty, transport or restricted housing conditions have been reported to elicit responses in behavioural, cardiovascular, endocrine, renal, gastro-intestinal, and haematological parameters. These and other parameters that change during stress may thus be indicative of poor welfare. However, several sources of misinterpretation have to be considered before stress responses may be used as valid indicators of welfare. Although analogous to the human situation, especially chronic stress may impair welfare, most studies deal with acute stress and do not address chronic stress and related phenomena. Adaptation may counteract the initial stress response and render parameters of acute stress useless for assessing chronic stress. Adaptations to stress are thus in themselves indicative of reduced welfare. Such adaptations may be discovered by challenging a stress responsive system. Additional studies are recommended to investigate acute stress parameters as possible indicators of chronic stress. Differences in stressor properties and in individual characteristics of dogs introduce variability in stress responses. Such variability will complicate a valid interpretation of stress responses with regard to welfare. Obtaining and applying fundamental knowledge of stress responses in dogs and measuring more than one stress parameter are proposed to minimize the risk of misinterpreting measurements of stress.