Dog Behavior Traits Connected to Salivary Cortisol Levels and Serotonin Activity

In a significant stride toward understanding the biological underpinnings of canine behavior, a new study published in the open-access journal PLOS One on February 4, 2026, reveals intriguing associations between canine temperament and salivary concentrations of cortisol and serotonin. Conducted by Minjung Yoon and colleagues at Kyungpook National University in the Republic of Korea, this research casts light on how physiological markers could complement observational assessments of dog behavior, potentially revolutionizing how we evaluate canine suitability for various roles such as pets, working dogs, or therapy companions.

Temperament evaluation in dogs is critical for ensuring they are well-suited to their environments and responsibilities, particularly in roles demanding specific behavioral traits. The Wesen test, a commonly used temperament assessment tool, relies heavily on human observation to gauge dogs’ reactions to a series of controlled social and environmental stimuli. These include responses to being alone, interactions with strangers, and behaviors indicative of anxiety, fear, confidence, or relaxation. Though widely used, the test’s subjective nature has been a point of contention, motivating researchers to seek objective measures that could supplement or validate observational data.

Yoon and colleagues took on this challenge by incorporating biochemical analysis into the temperament assessment framework. The study sample consisted of twenty-four dogs spanning various breeds to ensure broader applicability of findings. Each dog underwent the Wesen test while researchers simultaneously collected saliva samples before and after the assessment to measure cortisol, a hormone closely linked to stress response, and serotonin, a neurotransmitter often associated with mood regulation and positive social behavior. This integration of physiological data aimed to uncover correlations between hormone levels and behavioral scores from the test.

Findings demonstrated a compelling negative correlation between cortisol levels and positive temperament scores. Dogs exhibiting behaviors traditionally interpreted as favorable—such as calmness, confidence, and reduced anxiety—tended to have lower baseline cortisol concentrations. More notably, these dogs showed a diminished cortisol spike following the stress-inducing stimuli of the Wesen test compared to dogs with lower scores. This suggests that their hypothalamic-pituitary-adrenal (HPA) axis, which governs stress hormone release, was less reactive, indicating a possibly more resilient and balanced stress physiology underpinning their demeanor.

In exploring the serotonergic component of temperament, the study assessed salivary serotonin in sixteen of the participating dogs. Although the correlation between serotonin levels and behavior scores did not reach statistical significance, an interesting pattern emerged. Dogs with higher Wesen test scores exhibited significantly elevated serotonin levels prior to testing, implying that intrinsic serotonergic activity might positively influence temperament or that dogs with better behavioral profiles maintain a more regulated serotonergic system. This finding aligns with existing literature correlating serotonin with reduced aggression and improved mood stability in canines.

The research team exercised caution in interpreting these correlations, acknowledging the limited sample size and the absence of causative conclusions. The study stops short of declaring that modified hormone concentrations directly cause improved temperament or vice versa. Instead, it proposes that these physiological markers—particularly cortisol and serotonin measured non-invasively through saliva—might serve as reliable biomarkers alongside traditional behavioral assessments. Such biomarkers could help overcome the subjectivity inherent in observer-based tests and provide additional layers of precision in temperament evaluation.

From a practical standpoint, the implications of this research are vast. Identifying objective physiological parameters linked with desirable canine traits could refine selection criteria for working dogs engaged in military, police, guide, or therapy contexts, where temperament stability is crucial. Enhanced screening methods grounded in biology could reduce training failures and improve welfare by ensuring dogs placed in demanding roles possess the psychological resilience and sociability required for success.

Moreover, the integration of hormone analysis might support more informed pet adoption decisions. Prospective dog owners could benefit from understanding a dog’s stress reactivity and mood regulation tendencies before commitment. This would potentially decrease relinquishment rates owed to behavioral incompatibilities and foster better human-animal bonds through tailored matching processes.

Technically, measuring cortisol and serotonin via saliva presents advantages over more invasive blood draws, facilitating repeated, stress-minimal sampling in diverse scenarios. Salivary assays have become increasingly accurate and accessible, making them practical for veterinary clinics and research settings alike. The study’s use of pre- and post-test measurements allowed a dynamic view of hormonal fluctuations in response to specific stimuli, offering insights into both baseline status and reactivity profiles.

This study, however, urges further research with larger cohorts to validate and expand on these initial findings. Future work could explore additional neurotransmitters and hormones implicated in emotional regulation, investigate breed-specific variations, and evaluate how environmental factors interact with biological mechanisms to shape temperament. Longitudinal designs might uncover how these physiological markers evolve through development, training, or in response to chronic stress.

In conclusion, the pioneering work by Yoon et al. underscores the promise of blending behavioral science with biochemical analysis to enrich our understanding of canine temperament. By harnessing objective biomarkers such as salivary cortisol and serotonin alongside established observational tests, we edge closer to an integrated, evidence-based approach that enhances animal welfare, optimizes working dog deployment, and refines human-canine relationships. This melding of physiology and psychology marks a forward leap in canine behavioral science, paving the way for more precise diagnostics and interventions in the years ahead.

News Publication Date: 4-Feb-2026

Web References: http://dx.doi.org/10.1371/journal.pone.0337781

References:
Jung Y, Song Y, Yang K, Yoo K, Heo Y, Yoon M (2026) Associations between canine temperament and salivary concentrations of cortisol and serotonin. PLoS One 21(2): e0337781.