Exploring the relationship between plasma and salivary levels of oxytocin, vasopressin, and cortisol in beagles: A preliminary study.

Oxytocin, vasopressin, and cortisol are widely used as biomarkers to assess the temperament or emotional state of dogs. Typically, these levels are measured in blood; however, this invasive procedure can induce acute pain and stress. Considering the welfare of dogs, it is necessary to replace these procedures with noninvasive methods. Saliva sampling has emerged as a promising, noninvasive alternative for measuring hormonal levels. Nonetheless, it remains unclear whether saliva samples accurately reflect plasma hormonal levels in dogs. The objective of this study was to evaluate the correlations of oxytocin, vasopressin, and cortisol levels between plasma and saliva samples. We simultaneously collected blood and saliva samples from fifteen beagles, aged six, including eleven females and four sterilized males. Due to the limited availability of saliva samples, each analysis was performed on 5-11 dogs. Hormonal levels were quantified using commercial ELISA kits. Linear regression analysis and Pearson's correlation coefficient were used for statistical analysis. Our findings revealed no significant correlation between oxytocin or vasopressin levels in the plasma and salivary samples. However, a significant positive correlation was observed between cortisol levels in plasma and saliva samples. Additionally, oxytocin and vasopressin levels were positively correlated in both plasma and saliva samples. A positive correlation was found between the plasma cortisol and oxytocin levels, whereas no correlation was observed between the salivary cortisol and oxytocin levels. This study provides a foundation for understanding hormonal relationships across different matrices, contributing to the development of alternative sampling methods that prioritize animal welfare.