Evaluation of salivary vasopressin as an acute stress biomarker in healthy dogs with stress due to noise and environmental challenges

BACKGROUND: Stress is associated with various detrimental changes in physiological health that affect an animal’s quality of life. The hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic-adreno-medullar (SAM) axis are two main physiological pathways that constitute the stress response of an organism. Arginine vasopressin (AVP) is a mediator of the HPA axis and is known to be related to social behaviours and stress. The serum concentration of AVP is higher in more aggressive dogs and humans with post-traumatic stress disorder. Salivary biomarker analysis is a non-invasive method to assess stress. The purpose of this study was to evaluate the possibility of using salivary AVP as an acute stress biomarker in dogs. Salivary AVP concentration was measured before and after exposure to all relevant environmental stimuli (i.e. car trip to the lab, physical examination by the veterinarian, and sampling procedure,) and then after 30 min of vacuum noise exposure. Behavioural assessments, physiologic parameter assessments, and serum cortisol analysis were conducted in combination. Statistical analysis was conducted separately in the total study population, the less stressed group, and the more stressed group, respectively. RESULTS: Based on stress behaviour analysis scores, 28 dogs were classified into less or more stressed groups. All four physiologic parameters (blood pressure, body temperature, heart rate, and respiratory rate) were significantly increased after noise and environmental challenges, in the more stressed group. Serum cortisol did not show any significant change. Salivary AVP significantly decreased after noise and environmental stimulation in the more stressed group but not in the less stressed group. Salivary AVP and blood pressure changes were negatively correlated in the more stressed group. CONCLUSION: Salivary AVP may be a potential acute stress biomarker in dogs.