Hot dogs: thermography in the assessment of stress in dogs (Canis familiaris) : a pilot study

Infrared thermography (IRT) represents a non-invasive method to investigate stress responses in animals. Despite the large existing literature about stress responses in dogs, the potential use of IRT in assessing dogs' stress reactions has not been investigated so far. This study evaluates the usefulness of IRT to assess dogs' emotional responses to an unpleasant and stressful event. After a preliminary test, aimed to evaluate the correlation between eye temperature and rectal temperature in dogs in a stressful situation, a sample of 14 adult healthy dogs was observed during a standardized veterinary examination, carried out by an unfamiliar veterinarian in the presence of their owners. Dogs' behaviors and eye temperatures were recorded before the start of the veterinary visit, during, and after the clinical examination. Dogs' levels of activity and stress-related behaviors varied across the different phases of the visit. Interestingly, the dogs showed an increase in eye temperature during the examination phase compared with both pre-examination and post-examination phases, despite a concomitant significant decrease in their level of activity. However, it also emerged that the thermographic camera, although remote and non-invasive, was disturbing for the dogs, to some extent, as they showed avoidance behaviors, including averting their gaze and/or turning their head, exclusively when the thermographic camera was oriented to them. Overall results suggest that IRT may represent a useful tool to investigate emotional psychogenic stress in dogs. Nevertheless, further research is needed to establish the specificity and sensitivity of IRT in this context and to assess how different dogs' characteristics, breed, previous experience, and the nature and severity of the stressor could influence the magnitude and type of the stress response.