The gut microbiome of companion animals influences behavior, immunity, and emotional states, with disruption through inappropriate diet, antibiotic overuse, and stress causing welfare effects that are only beginning to be understood.
The companion animal microbiome represents an emerging welfare dimension that connects diet and antibiotic management to behavioral and emotional welfare outcomes. Animals with disrupted microbiomes show increased anxiety and stress responses — a welfare effect that is invisible to owners who focus on the immediate cause of antibiotic use rather than downstream microbiome effects. Diet diversity, fiber provision, and judicious antibiotic use support microbiome health and through it, behavioral and emotional welfare.