The gut microbiome of companion animals affects not only physical health but also behaviour and emotional welfare; diet and antibiotic use significantly shape microbiome composition.
The relationship between gut microbiome and welfare in companion animals is an emerging frontier that extends welfare science beyond the visible. Microbiome disruption from antibiotic use, poor diet, or chronic stress affects physical health through immune function, but also behaviour and emotional regulation through the gut-brain axis. A dog or cat experiencing chronic stress will show microbiome alterations that in turn may exacerbate stress-related conditions. Understanding this bidirectional relationship provides additional motivation for reducing unnecessary antibiotic use, providing appropriate nutrition, and managing chronic stress in companion animals.