Effect of the Probiotic Bacillus subtilis DE-CA9TM on Fecal Scores, Serum Oxidative Stress Markers and Fecal and Serum Metabolome in Healthy Dogs

There is increasing interest in the use of Bacillus species as probiotics since their spore-forming ability favors their survival in the acidic gastric environment over other probiotic species. The subsequent germination of B. subtilis to their vegetative form allows for their growth in the small intestine and may increase their beneficial effect on the host. B. subtilis strains have also previously been shown to have beneficial effects in humans and production animals, however, no reports are available so far on their use in companion animals.The goal of this study was therefore to investigate the daily administration of 1 × 109 cfu DE-CA9TM orally per day versus placebo on health parameters, fecal scores, fecal microbiome, fecal metabolomics, as well as serum metabolomics and oxidative stress markers in ten healthy Beagle dogs in a parallel, randomized, prospective, placebo-controlled design over a period of 45 days.DE-CA9TM decreased the oxidative status compared to controls for advanced oxidation protein products (AOPP), thiobarbituric acid reactive substances (TBARS) and reactive oxygen metabolites (d-ROMS), suggesting an antioxidant effect of the treatment. Fecal metabolomics revealed a significant reduction in metabolites associated with tryptophan metabolism in the DE-CA9TM-treated group. DE-CA9TM also significantly decreased phenylalanine and homocysteine and increased homoserine and threonine levels. Amino acid metabolism was also affected in the serum metabolome, with increased levels of urea and cadaverine, and reductions in N-acetylornithine in DE-CA9TM compared to controls. Similarly, changes in essential amino acids were observed, with a significant increase in tryptophan and lysine levels and a decrease in homocysteine. An increase in serum guanine and deoxyuridine was also detected, with a decrease in beta-alanine in the animals that ingested DE-CA9TM.Data generated throughout this study suggest that the daily administration of 1 × 109 cfu of DE-CA9TM in healthy Beagle dogs is safe and does not affect markers of general health and fecal scores. Furthermore, DE-CA9TM administration had a potential positive effect on some serum markers of oxidative stress, and protein and lipid metabolism in serum and feces.