The gut microbiome is not technically an organ, but it does have important functions in puppies and kittens, including training the immune system.1 A balanced microbiome primes and stimulates the immune system, aids in defense against intestinal pathogens, and provides diverse health benefits to the body.2-4

Unfortunately, newborn mammals like puppies and kittens are born with an underdeveloped gut microbiome and low immunity, which increases their susceptibility to invading pathogens.1,4 The nutritional status of the mother and the immunomodulating nutrients they receive from colostrum largely determine the bacteria that colonize before and during birth.1,5,6


The growing period is critical to long-term health in dogs and cats.1 The gut microbiome is more sensitive to disruptions during this time, including those caused by antibiotics. Negative changes in the microbiota can cause issues later in life, such as increased metabolic and immune disorders in animals.1,6,7

Because puppies in particular often experience acute diarrhea, it is especially important to support the development of a healthy gut microbiome instead of relying on antibiotics.6 Similarly, studies have shown that treatment with antibiotics in kittens can delay maturation of the gut microbiome for three months.8


The early developmental window presents a unique opportunity to intervene. Interventions seeking to modulate the gut microbiota in puppies may be more effective in establishing a healthy gut than those undertaken in adult dogs.9 Because the brain and immune system are still developing in the postnatal period, the nutritional environment can either support or disrupt the maturation and development processes.1,6 Experiences and exposures during critical periods of development can have cumulative effects on behavioral traits, cognitive abilities, trainability, health, and performance.6

As such, nutritional interventions that optimize the composition and function of the microbiome can improve the health of both cats and dogs and support their over-all digestive and immune health.

Whereas antibiotics and environmental stress can cause dysbiosis in newborn puppies and kittens, nutritional support can positively affect gut microbiome health by helping to balance bacterial species.1 Supplementation with a natural plant polyphenol in puppies alleviates oxidative stress and inflammation associated with environmental stress by supporting the gut microbiome.10 Additionally, prebiotics, probiotics, and postbiotics can help support a healthy gut microbiome.2,11 Finally, providing a diet that meets nutritional requirements, as well as enhances the function of the microbiome, can significantly improve and support the holistic health of cats and dogs.


Keri Barron, PhD, is the Scientific Nutrition Writer for Standard Process Inc. located at the Nutrition Innovation Center in Kannapolis, North Carolina. Her work involves creating educational materials and translating scientific articles for audiences to support health and wellness. Keri has a B.S. in Nutritional Biochemistry and Metabolism and M.S. in Nutrition from Case Western Reserve University in Cleveland, Ohio. She continued her studies at the Nutrition Research Institute, a remote campus of the University of North Carolina at Chapel Hill, earning a PhD in Nutrition.


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