Right at this second, there are trillions of bacteria and microbes living in and on your body in areas known as microbiomes. People, pets, plants, and even places can be host to microbiomes . And each is a complex living universe; studies have shown that there are 10 times more microbes in a living organism than the number of cells present in the organism itself 
While kind of gross to think about, this isn’t actually a bad thing. Many of these microbiomes contain good bacteria that can help the body perform physiologic functions and protect against pathogens.
So what does this all mean for your dog or cat? Well, your pet’s body contains microbiomes, which means their overall health and wellness can be impacted by those microbiomes, too.
Many people take probiotics to keep their gut microbiome balanced and some pet parents are starting to wonder if Fido or Fluffy would benefit from the same.
There’s a fast-growing market for pet probiotics. But, like any emerging science, pet parents would do well to learn a bit more about them before starting to administer these supplements to their dogs and cats.
What are Probiotics for Dogs and Cats?
“Probiotics are live organisms that help promote or improve the health of the gastrointestinal flora (bacteria) after they are ingested in appropriate quantities,” explains Karah Burns DeMarle, DVM, a doctor on the internal medicine team at NorthStar VETS Emergency, Trauma, and Specialty practice in New Jersey.
Probiotics are sometimes confused with prebiotics, which are the non-digestible food ingredients that nourish good bacteria in the gut . The fact that probiotics are alive is what differentiates them from prebiotics.
While the veterinary community generally agrees that probiotics can be beneficial for certain health issues and ailments, it’s still a relatively new area of study.
“There are many different theories about how they actually work,” Burns DeMarle says. “[One theory involves] increasing the numbers of ‘good bacteria’ in the gut, which changes the environment and makes it more difficult for pathogenic bacteria to grow.”
This means that probiotics have the potential to benefit your pet’s digestive health, preventing different types of intestinal distress. According to Medical Director Ronald Hamilton, DVM, of the Gulf Coast Veterinary Center in Tampa, Florida, probiotics can help restore balance to the gut’s microflora after it becomes disturbed — such as after taking antibiotics or eating something that affects the microbiome’s ecosystem. “[Probiotics] work by displacing pathogenic or potentially disease-causing bacteria with those that have potentially beneficial effects,” says Hamilton.
Further, there is data that suggests that the health of your pet’s gut microbiome can impact not just gastrointestinal health, but also overall health, affecting allergies, oral health, weight management, diabetes, and kidney disease, to name a few 
5 Myths Behind Probiotics for Dogs and Cats
While pet probiotics are a relatively new addition to many pet health and wellness regimens, plenty of myths and misinformation have taken hold since they emerged.
Here are five of the biggest myths pet parents should know about probiotics for pets—and the facts that dispel them.
Myth 1: Probiotics are a cure-all.
Administering probiotics does not guarantee your pet’s good health. There still isn’t much scientific data about how probiotics work in pets. “We do not fully understand the complexity of the microbiome in dogs and cats, and therefore our knowledge on the true benefits of probiotics in these species are lacking,” Burns DeMarle says. “There have been multiple studies looking at the efficacy of these products in our small animal companions and the results are extremely variable.”
She adds that while more research is warranted, she believes that probiotics can positively impact patients’ health and doesn’t see any harm in recommending them. “I do think that they have potential to help. Have I used them in my patients? Absolutely.”
Myth 2: All probiotics are the same.
The amount and variety of bacteria that inhabit our pets’ microbiomes is simply staggering. As such, not all probiotics are the same, and different strains of bacteria have different effects on the host.
Here’s just one illustration of how that translates to the real world: “There have been multiple studies in the veterinary literature that have assessed the use of probiotics for different health conditions in cats and dogs,” Burns DeMarle says. “Enterococcus faecium has been shown to increase the diversity of bacteria in dogs with inflammatory bowel disease (IBD). Other potential uses include canine atopic dermatitis, feline herpes virus infections, and chronic kidney disease.”
While many veterinarians, like Burns DeMarle, may agree that it is worth pet probiotics a try, that doesn’t mean just any probiotic will do. Pet parents can research the specific strains that address their pet’s health issues or ask their veterinarian for recommendations. As with medications, be sure to monitor time and amount of the probiotic dose, and track any health changes to measure impact.
Myth 3: Probiotics are highly regulated.
Both Hamilton and Burns DeMarle stress that probiotics are not well regulated and that pet parents cannot always believe what is on the label.
“Probiotics are not drugs and therefore are not regulated as tightly. Studies have shown that many of these products have claims on their labels that are not supported by appropriate research,” Burns DeMarle explains.
Hamilton adds that several companies manufacture untested probiotics and that the strains listed on the bottle are not necessarily the strains in the bottle.
Further, a study from the Journal of the American Veterinary Medical Association showed that out of 13 probiotics, only two had labels that accurately described what sort of organisms and concentrations were in the products. 
In the absence of regulations against misleading or just plain deceptive probiotics claims, the amount of information on the product label and the level of detail are two key clues that can help pet parents figure out if they’re dealing with a reputable manufacturer. Look for labels that contain “specific (and valid) bacterial names (genus and species), with no spelling errors and a clear statement of the number of viable organisms that are expected.” 
Myth 4: The number of live cultures at the time of manufacture is the number of live cultures you’ll get.
For probiotics to be effective, they must still be alive. Many commercially-available probiotics will claim each dose had a certain number of live cultures “at the time of manufacture.” This is a misleading claim because that number is not necessarily true by the time the probiotic reaches the consumer. Depending on a supplement’s shelf life, half of those cultures or more could be dead by the time it reaches consumers. If a pet parent sees this verbiage on a probiotic label, it’s a red flag.
Once again, probiotics are not well regulated. Medical professionals have been calling for improved quality control in probiotics for some time (6) and pet owners must be diligent regarding sourcing their supplements from trusted brands.
Myth 5: All probiotic pet food has the same benefits as probiotic supplements.
Veterinarians note that store-bought pet foods touting the addition of “live cultures” may not deliver on that promise. Keeping probiotics viable in commercial pet food requires careful attention to the organisms’ stability during manufacturing, shipping, and storage, which is not always an easy matter for pet food manufacturers.
If the idea of probiotic pet food seems like a win-win to you, be sure to do your research and make sure “probiotic” isn’t just a buzzword on the packaging. Look for language that speaks to the importance of strain stability and whether the product has been tested to ensure the probiotics are robust enough to survive commercial manufacturing practices. A high-quality pet food, produced by a reputable manufacturer with attention to research and development, is more likely to contain viable probiotics than a pet food manufacturer without a full scientific team.
How to Find the Right Probiotic for Your Pet
Even with all of these myths debunked, pet probiotics remains a complex topic. So how can pet parents navigate the potential benefits while avoiding the pitfalls?
Burns DeMarle and Hamilton agree that pet parents looking to start their dog or cat on probiotics should consult with their veterinarian to find the correct strain and the best manufacturer.
“Although [probiotics] are not drugs and a prescription is not required, a veterinarian can help guide pet parents as to which product may actually be the most beneficial to their pet. Additionally, their veterinarian can help direct them toward a product from a reputable manufacturer,” Burns DeMarle concludes.