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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., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The purpose of this study was to evaluate the influence of exercise on plasma tryptophan (TRP) and free serotonin (f5-HT), whole blood-5-HT (WB-5-HT) and f5-HT/WB-5-HT ratio in Italian Saddle horses. Six clinically healthy Italian Saddle horses were subjected to a 450 meters obstacles course. Blood samples were collected from each horse by jugular venipuncture using vacutainer tubes with K(3)-EDTA at rest, immediately after exercise, and after 30 min. TRP, f5-HT and WB-5-HT were analyzed by HPLC. Immediately after exercise, statistically significant increases of f5-HT (p <0.001) and WB-5-HT (p <0.001) were observed. After 30 min, f5-HT and WB-5-HT decreased compared to immediately after exercise, but were still significantly higher than rest values (p <0.01 and p <0.05, respectively). A significant linear regression between f5-HT and WB-5-HT was observed during experimental conditions. f5-HT and WB-5-HT modifications after exercise suggest an important role of peripheral serotoninergic markers in response to physical activity. The possible source of extra serotonin detected after show jumping should be clarified by further investigation.

The aim of this study was to investigate whether plasma serotonin (5-hydroxytryptamine [5-HT]) was associated with the presence of foot pad dermatitis (FPD) in laying hens. FPD birds (n = 20) and healthy individuals (n = 22) were included. Plasma 5-HT was investigated. FPD laying hens showed significantly higher 5-HT levels (median = 6 µmol/L) compared with healthy individuals (median = 4.28 µmol/L, P <.001). When present, FPD were scored as either 1 (n = 12) indicating mildly to moderately abnormal or 2 indicating severely abnormal (n = 8). The subjects whose lesions scored 2 had higher plasma 5-HT levels than those whose lesions scored 1. Inflammatory mechanisms seem to be related to plasma 5-HT levels in laying hens. Assessing plasma 5-HT could be useful to evaluate chicken welfare. [ABSTRACT FROM AUTHOR]

The monoamine neurotransmitter serotonin (5-hydroxytryptamine [5-HT]) is involved in neuronal excitability, regulates mood and cognition, and is implicated in the regulation of a wide range of social behavior. Understanding its role in social behavior would be useful in understanding and improving human-animal interactions, in particular, the human-dog interaction. Examination of canine social behavior is crucial for screening shelter dogs to be placed for adoption or for identifying dogs that need behavioral intervention. Behavior problems in dogs can arise because of long-term stays in shelters. The aim of this study was to determine whether serum 5-HT is related to behavioral responses in shelter dogs. Fourteen mixed-breed castrated male dogs, with no signs of aggressive behavior toward humans, were selected for exploring the relationship between 5-HT and social behavior in dogs. These dogs were individually observed by an operator during a sociability toward humans test, and their behavioral responses toward the operator were evaluated using a simple test constituted by 7 episodes: Operator approaches the door of the pen, coaxes the dog, attempts to sit the dog and ask for its forelimb, attempts to put a collar on the dog, walks with the dog on a leash, throws a tennis ball against a wall and plays alone, and throws the tennis ball and invites the dog to play with him once. Each episode was scored from 2 to 8, with low scores representing the most fearful dogs. Blood samples were drawn from the cephalic vein during routine health checks, and some serum was retained for 5-HT analysis. A weak linear correlation between the behavioral scores from operator-dog interactions and 5-HT levels ( r 2 = 0.31, P < 0.05) was found. According to these preliminary data, markers of the serotoninergic system could be related to the sociability of dogs toward humans. [ABSTRACT FROM AUTHOR]