The aim of this study was to evaluate the effects of intraspecific social exposure (socialization vs rest) and habituation factors on the levels of urinary serotonin and cortisol [corrected respectively for creatinine to give the serotonin-creatinine ratio (5-HT/Cr) and cortisol-creatinine ratio (C/Cr)] and how they fluctuate in dogs. The frequency of marking during social sessions was recorded to evaluate its relationship with physiological parameters. The effects of covariates on 5-HT/Cr and C/Cr were assessed using a linear mixed models. 5-HT/Cr values were higher at dawn than at dusk during resting days, however, this difference is less evident after socialization sessions. During rest days, there was a trend for a decrease in C/Cr between dawn and dusk, while during social exposure days there was an opposite trend. Significant interactions were found between social exposure vs rest (P = 0.0005) and social exposure vs sessions (P = 0.002). Urine marking was more frequent in male than female dogs. The frequency of urine marking also appeared to be positively associated with C/Cr. Non-invasive monitoring of physiological markers could be a useful tool in assessing behaviour modulation following intraspecific socialization exposure. C/Cr was characterized by high individual variability and interactions with examined factors. The identification of new markers such as serotonin for assessing welfare in dogs is highly desirable.
Keywords: Cortisol; Dog; Non-invasive monitoring; Serotonin; Social exposure; Urine.
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