Probiotics for Supporting Gut Health in Dogs and Cats: Benefits and Side Effects

In recent years, the pet food industry has increasingly focused on the “gut environment” to help maintain the health of dogs and cats. The gut is often called the “second brain” because it plays a major role not only in digestion and nutrient absorption, but also in immune function and whole-body health. One of the most important keys to supporting a healthy gut environment is probiotics. These beneficial microbes help maintain balance in the intestinal tract and support overall wellness.

What Are Probiotics?

Probiotics are beneficial microorganisms (often referred to as “good bacteria”), or foods and supplements that contain them, designed to help maintain and increase helpful bacteria in the gut. When pets have a sufficient level of beneficial bacteria, they are far less likely to suffer from diarrhea, constipation, vomiting, and other digestive discomfort.

As probiotic levels increase, nutrient absorption can improve and digestion can remain healthier—while also supporting immune function. Probiotics may also help the body defend against infection-causing viruses. In addition, probiotics can produce certain vitamins such as B vitamins and vitamin K.

Probiotics can be especially effective when used alongside a balanced diet that meets all of a pet’s nutritional needs. Pets can consume probiotics through pet supplements and probiotic-containing dog or cat food.

Additional note

The word “probiotic” comes from Greek: pro (“for”) + biotics (“life”), meaning “for life.”

Types of Probiotics

Strain	Key characteristics	Main benefits	Heat resistance
Bacillus subtilis	Aerobic soil bacterium that forms spores. Widely used in products for pets and humans.	Gut support, pathogen suppression, immune support	★★★★☆ (Very strong)
Bacillus coagulans	Heat-resistant spore-forming bacterium that produces lactic acid. Used in gut-support products for humans and pets.	Improved bowel movements, diarrhea prevention, lactic acid production	★★★★☆ (Very strong)
Bacillus clausii	Spore-forming bacterium known for antibiotic resistance traits.	Supports gut health during antibiotic use, reduces diarrhea	★★★★☆ (Very strong)
Lactobacillus acidophilus	A representative lactic acid bacterium naturally present in humans and animals.	Helps regulate gut pH, supports immunity, improves bowel movements	★☆☆☆☆ (Heat-sensitive)
Lactobacillus casei	Widely distributed in the digestive tract; relatively acid-tolerant.	Gut support, helps with lactose digestion	★☆☆☆☆ (Heat-sensitive)
Lactobacillus rhamnosus	Popular in human and pet supplements; high ability to colonize.	Reduces diarrhea, supports allergy prevention, strengthens immunity	★☆☆☆☆ (Heat-sensitive)
Bifidobacterium bifidum	Common in newborns and animal intestines; can colonize the gut.	Produces acetic acid, improves bowel movements, suppresses harmful bacteria	★☆☆☆☆ (Heat-sensitive)
Bifidobacterium animalis	Used in pet food and yogurt.	Gut support, reduces stool odor, improves stool quality	★☆☆☆☆ (Heat-sensitive)
Clostridium butyricum	Butyrate-producing bacterium important for energy supply in the gut.	Protects colon lining, reduces inflammation, supports gut health	★★☆☆☆ (Somewhat heat-tolerant)
Streptococcus thermophilus	Lactic acid bacterium used in yogurt production.	Supports lactose digestion; can enhance effects when combined with other strains	★★☆☆☆ (Somewhat heat-tolerant)
Enterococcus faecium	Common in veterinary gut-support products; relatively environment-resistant.	Balances gut microbiota, supports defense against infection	★★☆☆☆ (Partly heat-tolerant)
Saccharomyces boulardii	Yeast; resistant to antibiotics and stomach acid; strong gut-support activity.	Helps prevent antibiotic-associated diarrhea, binds toxins, supports immunity	★★★☆☆ (Fairly strong)

Probiotics vs. Prebiotics

Both prebiotics and probiotics are essential for gut health, but they play different roles in maintaining intestinal balance.

• Probiotics: beneficial microorganisms that help maintain and increase good bacteria in the gut.
• Prebiotics: dietary fibers that serve as “food” for beneficial bacteria.

Without prebiotics, beneficial bacteria cannot thrive and multiply effectively. In other words, probiotics bring beneficial microbes into the gut, and prebiotics support them.

Beneficial bacteria can suppress the growth of harmful bacteria and help maintain digestive health. However, when beneficial bacteria are insufficient and harmful bacteria become dominant, pets may experience issues such as:

When harmful bacteria increase…

Benefits of Probiotics

When taken in the right amount and at the right time, probiotics help increase beneficial bacteria in the digestive tract. By reducing harmful bacteria and supporting beneficial bacteria, probiotics can improve digestive health in dogs and cats—and their benefits may extend to many areas of health, including:

Probiotics for Dogs

Probiotics for dogs are most commonly used to help prevent diarrhea. They may also be beneficial in the treatment or prevention of bacterial infections and inflammatory bowel disease. In some cases, they may also support other health concerns such as allergies, obesity, and diabetes.

Should you give your dog probiotics?

Considering the potential benefits, many dogs can benefit from probiotics. You may also wonder, “Is it okay to give my dog probiotics every day?”

The answer is yes. Many veterinarians recommend daily probiotics to support digestive health and overall wellness.

As explained above, probiotics contain beneficial bacteria that support your dog’s digestive tract. If beneficial bacteria are lacking, dogs may face a higher risk of health issues such as allergies, obesity, and irritable bowel syndrome (IBS).

A healthy digestive system is closely linked to a healthy immune system.

What are the best probiotics for dogs?

The best probiotics for dogs are those formulated specifically for dogs. If you’re unsure what your dog needs, consult a veterinarian about symptoms and concerns to determine which probiotic is most appropriate.

If you don’t know which type to give—or how often—always consult a veterinarian. Incorrect use can cause digestive upset such as diarrhea or vomiting. Choosing the right probiotic and following proper feeding directions is essential.

Probiotics for Cats

Cat probiotics are commonly used for digestive issues such as diarrhea, constipation, and IBS. They may also support treatment for conditions like inflammatory bowel disease (IBD), colitis, and chronic enteritis.

Should you give your cat probiotics?

Just like dogs, cats can also benefit from probiotics. A healthy gut environment is a foundation of good health, and probiotics can help support it.

Probiotics help maintain a natural balance of microbes in the cat’s digestive system, supporting better overall health and stronger resistance to infections, diarrhea, constipation, and skin issues.

Probiotics may also help reduce stress in cats. Common stress triggers include moving to a new home, changes in the environment, or adjusting to new situations.

What kind of probiotics should you give your cat?

If a veterinarian prescribes a specific probiotic, use only that type. If it doesn’t suit your cat, discuss alternative brands or strains with your veterinarian.

Unless specifically instructed by your veterinarian, do not use human probiotics for cats (except when a veterinarian approves it).

If you’re unsure which type to use or how often, consult a veterinarian.

Are There Side Effects of Probiotics?

Although probiotics can change the gut microbiota, no serious side effects have been reported in dogs and cats to date. This may be related to the fact that many probiotic products use a single strain or are provided in relatively small amounts.

However, some probiotic supplements include flavorings or stabilizers that could pose an allergy risk. Confirm ingredient details with the manufacturer or your veterinarian.

In human medicine, concerns have been raised about probiotic use in patients with severely weakened immune systems, but this remains largely speculative.

More research is needed to evaluate whether long-term probiotic use could cause issues in pets. At present, probiotic use is generally considered very safe.

Dogs and Cats That May Particularly Benefit from Probiotics

Probiotic-containing foods and supplements can be beneficial even for healthy dogs and cats. However, probiotics may be especially helpful for pets that have the following concerns: