Scientists are learning that the tiny bacteria living in your dog’s or cat’s stomach and intestines play a huge role in keeping them healthy and happy. This review looked at all the research about pet gut bacteria in Australia, where almost 7 out of 10 homes have pets. Researchers found that what you feed your pet, where they live, and whether they’re overweight all change which bacteria live in their gut. Interestingly, the bacteria in your pet’s digestive system can even be shared with you and your family. Understanding these bacteria better could help vets treat sick pets and keep healthy ones feeling great.

The Quick Take

  • What they studied: How the bacteria living in dogs’ and cats’ digestive systems affect their health, and what factors change which bacteria are present
  • Who participated: This was a review of existing research, so it didn’t study specific animals directly. Instead, scientists looked at many previous studies about pet gut bacteria, mostly focusing on research from Australia
  • Key finding: The type and amount of bacteria in your pet’s gut depends heavily on their diet, weight, living situation, and whether they have health problems. The same bacteria can sometimes be shared between pets and their owners
  • What it means for you: Feeding your pet quality food and keeping them at a healthy weight may help their gut bacteria stay balanced, which could improve their overall health. However, more research is needed before vets can recommend specific changes based on gut bacteria

The Research Details

This was a review article, which means scientists read and summarized all the important research that’s already been done on pet gut bacteria. They looked at studies about what bacteria live in dogs and cats, how diet changes these bacteria, and how gut bacteria connect to diseases. The researchers focused especially on studies done in Australia, where pet ownership is very common.

The scientists organized information about four main types of bacteria that are most common in pets: Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. They also looked at how different things—like the food pets eat, whether they’re overweight, where they live, and if they have diseases—change which bacteria are present. They even explored whether bacteria can move between pets and their human families.

Review articles are important because they bring together everything scientists know about a topic so we can see the big picture. Instead of looking at just one study, reviewers can spot patterns across many studies and identify what we still need to learn. This helps vets and pet owners understand what’s really proven versus what still needs more research

This review was published in a respected veterinary science journal, which means experts checked the work before it was published. However, because this is a review of other studies rather than new research, the quality depends on the studies it reviewed. The authors were honest about what we don’t know yet and what questions still need answers, which is a good sign of careful scientific work

What the Results Show

The research shows that every dog and cat has a unique mix of bacteria in their gut, but certain types are common in most pets. Four main bacterial groups—Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria—are found in healthy dogs and cats, though the exact amounts vary between individual animals.

What your pet eats makes a big difference in their gut bacteria. Different types of food (like dry kibble versus wet food, or different protein sources) create different bacterial communities. This is important because the bacteria help your pet digest food and stay healthy.

Pets that are overweight tend to have different bacteria than pets at a healthy weight. Similarly, pets with chronic diseases or health problems often have different bacterial patterns than healthy pets. This suggests that gut bacteria might be connected to these health issues, though scientists aren’t sure yet if changing the bacteria could help treat the diseases.

Interestingly, researchers found evidence that bacteria can be shared between pets and their owners. This means some of the bacteria living in your dog’s or cat’s gut might also be living in your gut, and vice versa. This is an exciting new area of research that could help us understand how pets and people affect each other’s health

The review also found that environmental factors matter—where your pet lives and their daily activities can influence their gut bacteria. Additionally, some research suggests that microplastics (tiny pieces of plastic in the environment) might affect pet gut bacteria, though this is still being studied. The review noted that in Australia, where most households have pets, there’s a big opportunity to study how pet health connects to human health in a real-world setting

This review brings together scattered research and shows that scientists around the world are increasingly interested in pet gut bacteria. While previous studies looked at individual aspects (like diet or disease), this review connects all these pieces together. It shows that the field is moving toward understanding gut bacteria as a key part of pet health, similar to how human gut bacteria research has grown in recent years

The biggest limitation is that most research on pet gut bacteria is still new and limited. There aren’t enough studies comparing different regions or using the same methods, making it hard to know what’s ’normal’ for Australian pets specifically. Most studies are small and don’t test whether changing diet or other factors actually improves pet health long-term. The review also notes that we need more research on whether sharing bacteria between pets and humans is actually helpful or harmful. Finally, many studies haven’t been done in real-world settings with regular pet owners, so we don’t know how well findings apply to your own pet

The Bottom Line

Based on current evidence (moderate confidence): Feed your pet a consistent, quality diet appropriate for their age and health status. Keep your pet at a healthy weight through proper nutrition and exercise. If your pet has digestive problems or chronic health issues, talk to your vet about whether gut bacteria might be involved. Don’t make major diet changes without consulting your veterinarian, as this could disrupt your pet’s beneficial bacteria. Avoid unnecessary antibiotics, as these kill both harmful and helpful bacteria

All pet owners should know about gut bacteria basics, especially those with dogs or cats that have digestive issues, obesity, or chronic diseases. Veterinarians should be aware of this research when recommending nutrition and treatment plans. Pet food companies might use this information to develop better products. People with compromised immune systems should be aware that bacteria can be shared with pets, though this is rarely a serious problem. This research is less immediately relevant to people without pets, though it may eventually help us understand human health too

If you make changes to your pet’s diet or routine based on this research, you might notice changes in their digestion within 2-4 weeks, as gut bacteria can shift relatively quickly. However, improvements in overall health, weight, or chronic disease symptoms typically take 2-3 months or longer to become noticeable. Don’t expect dramatic changes—improvements are usually gradual

Want to Apply This Research?

  • Track your pet’s digestive health weekly by noting: stool consistency (firm, normal, or loose), appetite level (good, fair, or poor), and energy level (active, normal, or lethargic). Also log any diet changes and their dates. This creates a pattern you can share with your vet
  • Use the app to set reminders for consistent feeding times and portions, as routine helps maintain stable gut bacteria. If your vet recommends a diet change, use the app to gradually transition to the new food over 7-10 days (mixing increasing amounts of new food with old food) to avoid upsetting your pet’s bacteria balance
  • Monthly, review your pet’s digestive health trends in the app. If you notice persistent problems (diarrhea, constipation, or poor appetite lasting more than a week), share your app data with your vet. Track weight monthly and note any correlation between diet changes and digestive symptoms to identify what works best for your individual pet

This article summarizes scientific research about pet gut bacteria but is not a substitute for professional veterinary advice. Pet gut bacteria research is still developing, and findings may change as more studies are completed. Always consult your veterinarian before making significant changes to your pet’s diet, especially if your pet has existing health conditions, is taking medications, or has digestive problems. Do not use this information to diagnose or treat your pet’s health issues. If your pet shows signs of digestive distress, illness, or behavioral changes, contact your veterinarian promptly. This review was published in January 2026 and reflects research available at that time.