Effect of a novel nutraceutical supplement (Relaxigen Pet dog) on the fecal microbiome and stress-related behaviors in dogs: A pilot study

Anxiety and stress can trigger functional gastrointestinal disorders, whereas gastrointestinal symptoms can significantly increase anxiety and depression levels. These patterns are associated with the connection of the intestine and the brain through the “gut-brain axis,” a bi-directional communication of the nervous, endocrine, and immune systems. This clinical trial sought to investigate the effects of a novel nutraceutical supplement (Relaxigen Pet dog) containing natural anti-inflammatory compounds (CLA, Krill), pre/probiotics, 5-HTP, and L-theanine on stress-related behavior and to assess the connection between these stress-related behaviors and the fecal microbiome in dogs. Forty dogs, ranging in ages from 1 to 10 years, took part in this double-blind, placebo-controlled clinical trial. Ten dogs were control dogs without overt clinical signs of anxiety. Thirty dogs (experimental dogs) with signs of stress and anxiety were randomly assigned to the treatment (N = 20) and placebo (N = 10) groups. The treatment sample group (20 dogs balanced for sex) was administered with Relaxigen Pet dog tablets and the placebo group (10 dogs balanced for sex) with placebo tablets by mouth once a day for 60 days. A basic history questionnaire that focused on all aspects of dog's behavior, management, health issues, and behavioral signs of stress and anxiety, was collected at days 0, 30, and 60 for each experimental dog. A fecal sample was collected for all dogs at day 0 to compare the microbiome of the anxious and non-anxious dogs. The anxious dogs in the treatment and placebo dogs groups had a fecal sample collected again at 30 and 60 days. These samples were used to extract the DNA for microbiological analysis and to determine the leading bacterial group. ANOVA showed an influence of treatment × time and the group that received the treatment had a probability of improving greater than 10% (P ≤ 0.05). This study revealed a different structure of the intestinal microbiota between healthy dogs and those with stress-related behaviors at baseline. Supplementation with the Relaxigen seems to bring some changes in bacterial groups concentration in the treatment group of anxious dogs compared to the placebo one, but we must be very cautious in presenting these results due to the limitations of this pilot study (number of subjects, no dietary control, and no evaluation of microbiota over time for the control group dogs).