Are Human Probiotics good for cats?

How similar are we?

All living creatures are designed to live in a world that is teeming with countless microorganisms. Some of them may do us harm while others live in close contact, in a symbiotic relationship. We call them healthy flora, and they are located in the skin, mucosa, and any part or organ in the body that is in direct or indirect contact with the outside. The same holds true for pets, all mammals, and the majority of complex organisms.

What about your cat? In this article, we are going to review the digestive system of cats, how their gut microbiota supports their gastrointestinal function, and whether or not human probiotics are recommended for them.

A cat’s digestive system

Same as other complex organisms, the digestive system of a cat is designed to absorb the nutrients in food. Similar to our own digestive system, it holds thousands of bacteria known as gut microflora or beneficial bacteria. And these bacteria are also very helpful in promoting the absorption of nutrients, processing food, and promoting intestinal health.

Different from a human or a dog, cats have a sensitive digestive system. Many things can cause an upset stomach or changes in bowel habits. Their digestive system is not capable of holding too much food, either, not even in proportion to their size. That’s why they need to take frequent and very short meals, and take another bite only when the digestive system finishes processing the food.

Digestive Disorders of Cats

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The digestive system in cats also includes immune system cells, and it is the place where their white blood cells become trained and equipped to fight pathogens. That is also very similar to what happens in humans. Therefore, people often have the assumption that raising our gut microflora works the same way as raising the microflora of their cat. But that’s not always the case.

The difference between human and cat microbiota

Throughout their lifespan, a can goes through various changes in their diet, and they contribute to changing their microbiota, too. Very young cats and kittens 18 weeks or younger are usually populated with Lactobacillus and Bifidobacterium species. But they are not the only ones that populate their intestines. Bacteroides, Megasphaera, and Prevotella species start colonizing their gut after 42 weeks. In less than one year, the entire ecosystem of a cat changes dramatically, and it all depends on the food they eat.

Bacteroides species are usually present in healthy cats. This species has been studied in dogs, too, and they appear to have an important role in digesting carbohydrates. In cats, it seems that these species are also responsible for digesting crude protein, and they are more abundant in cats fed with high-diet protein.

For example, cats fed with a canned diet have a lower proportion of Lactobacilli and Bifidobacterium species. However, that does not mean they have an unhealthy gut microbiota. They are equally healthy than cats fed with a kibble diet or kittens fed with milk before weaning.

Enterococci species are also important for the intestinal health of felines. Enterococcus is very common in cats as they age, especially when they are fed with kibbled diets, and start appearing in the gut around the 18th week of age. Another species that populate a cat’s intestines is Faecalibacterium prausnitzii. This species is common regardless of the diet, and it seems to be very important to maintain a cat’s intestinal health.

Still other species we can find in the intestinal environment of cats include:

  • Peptostreptococcaceae species: In humans, these species are associated with fatty liver disease and other problems. In cats, it is a common species, prominent in healthy cats.
  • Eubacterium species: They ferment carbohydrates in the gut and produce butyrate in humans. In cats, they contribute to the digestibility of crude proteins.
  • Peptococcus species: Another species that contribute to digest proteins. The proportion of Peptococcus species is lower in cats with diarrhea and diabetes, suggesting an important role in their health.

The best probiotics for cats?

As you can see, the gut microbiota in cats is sometimes similar to that of humans, especially in their first year of age and as kittens. However, as they age and their diet changes, many species become abundant, and some of them are not common in humans. Moreover, a few species in the normal gut microbiota of healthy cats are found in the gut microbiota of humans with metabolic ailments. And not having them may cause digestibility issues in cats, especially when it comes to digesting protein and synthesizing butyrate.

Thus, even if no trial has approved or disapproved human probiotics for cats, it not likely that they will do them any harm, but they are not entirely recommended, either. It is not safe enough to assume that our probiotics will suit their gut, which has a different conformation and is much more sensitive than ours. Therefore, it is strongly recommended to use probiotics designed for cats.

Cat probiotics can be formulated as a pill or powders we can mix with a teat. The best probiotics should contain not only Bifidobacterium species as humans do. They also need Enterococcus species and at least a third species of the ones mentioned above if your cat is suffering from an acute gastrointestinal disease.

Probiotics are often recommended for cats when there’s a gastrointestinal issue, especially in cases of diarrhea. However, it is fine to use a probiotic supplement as a part of their daily routine, especially in an early stage of their development, and to promote good health and longevity. Using them alongside with antibiotics can be a good idea to prevent antibiotic-induced diarrhea.


Bermingham, E. N., Young, W., Butowski, C. F., Moon, C. D., Maclean, P. H., Rosendale, D., … & Thomas, D. G. (2018). The fecal microbiota in the domestic cat (Felis catus) is influenced by interactions between age and diet; a five year longitudinal study. Frontiers in microbiology9, 1231.

Suchodolski, J. S. (2011). Intestinal microbiota of dogs and cats: a bigger world than we thought. Veterinary Clinics: Small Animal Practice41(2), 261-272.

Deng, P., & Swanson, K. S. (2015). Gut microbiota of humans, dogs and cats: current knowledge and future opportunities and challenges. British Journal of Nutrition113(S1), S6-S17.

About Simon Bendini 78 Articles
Hello, I'm an expert in all things Probiotics. I also live and breathe what I write about: I take Probioitcs EVERY day. I want to help you discover the benefits of them too. Enjoy my humble site.

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