The gut microbiome of companion animals profoundly affects their health, immunity, and behavior, with diet and stress as primary modulators of microbiome composition and welfare outcomes.
Companion animal microbiome research is an emerging frontier with direct welfare implications. The gut-brain axis — the bidirectional communication pathway between the enteric nervous system and the central nervous system — means that microbiome disruption influences not just digestive health but behavioral welfare. Dogs with disrupted microbiomes following antibiotic treatment or diet change show increased anxiety indicators in some studies. Probiotic supplementation, particularly with Bifidobacterium longum, has shown anxiety-reducing effects in dogs in controlled trials. High-fiber, varied diets that support microbiome diversity align with both digestive health and behavioral welfare goals. Stress management matters for microbiome health as much as diet — the cascade of physiological changes during chronic stress, including cortisol-driven microbiome disruption, represents a direct pathway from psychological welfare to physical health.