Continuous intake of galacto-oligosaccharides containing syrup contributes to maintaining the health of household dogs by modulating their gut microbiota.

Interest is growing in the relationship of the microbiota and intestinal environment with health in companion animals. Galacto-oligosaccharides (GOS), typical prebiotics, are expected to provide benefits in dogs. Previous studies of GOS in dogs have involved dogs with similar rearing conditions and diets, which may have biased the results. We conducted an open study of 26 healthy dogs kept in households with diverse rearing environments in order to evaluate how the intake of a GOS-containing syrup affects the intestinal microbiota and its metabolites. Each dog was fed 1.2-4.8 g of the GOS-containing syrup (GOS 0.5-2.0 g equivalent) for 8 weeks. Fecal microbiota, fecal concentrations of organic acids and putrefactive products, fecal odor, and serum uremic toxin concentrations were evaluated before intake (0 weeks), during the 8-week intake period (4 and 8 weeks), and 4 weeks after intake (12 weeks). The activity of N-benzoyl-DL-arginine peptidase in dental plaque, which may be associated with periodontal disease, was evaluated at 0 and 8 weeks. Continuous intake of GOS resulted in changes in fecal microbiota, with a particularly marked increase in the abundance of Megamonas, which produces propionic acid. Other findings included a significant increase in the fecal acetic, propionic, and n-butyric acid concentrations. Additionally, significant decreases in fecal odor, fecal phenol concentration, and serum indoxyl sulfate concentration. Intake of GOS was also associated with a significant decrease in N-benzoyl-DL-arginine peptidase activity in dental plaques. These results suggest that continuous intake of GOS may contribute to canine health.