Here we describe long-lasting impacts on the microbiota-gut-brain (MGB) axis following administration of low-dose dextran sodium sulfate (DSS) to weaning mice (P21), including gut dysbiosis, colonic inflammation, and brain/behavioral deficits in adulthood (P56). Early-life DSS leads to acute colonic inflammation, similar to adult mice; however, it results in long-lasting deficits in the MGB axis in adulthood (P56), in contrast to the transient deficits seen in adult DSS. This model highlights the unique features of pediatric inflammatory bowel disease.