The contents of my cabinets — stocked with maca, goji berries, coconut water and the like — confirm it: I’m a sucker for food trends. So, when my social network lit up with talk of probiotics for dogs, I took cautious note. No harm, no foul if I want to get wacky nouveau with the things I eat, but what about my dog, whose nutritional needs I’m responsible for meeting?

“Probiotics,” a broad group of over 400 microorganisms that support a robust, disease-free body, are a longstanding favorite in the human supplement world. Now they are suddenly omnipresent in pet-supply stores as well. But are they suitable and safe for the canine constitution? To get to the bottom of these questions, as well as to better understand the fundamental mechanics and benefits of probiotics, I dug right in to get the lay of this microflora landscape. The result of these investigations? Four self-education steps that will help you map this molecular jungle, and safely separate the fish oil from the snake oil.

1. Understand the science.
None of us likes to think that our dogs are hosting microbes. But they are — hundreds of different kinds! And according to Mary Ellen Sanders, PhD, an internationally recognized leader in probiotic microbiology, that’s a good thing. In the canine gastrointestinal(GI) tract, probiotics promote health by “piggybacking on the important relationship between the normal immune system and microbes,” says Sanders.

More specifically, Sanders suggests that probiotics increase “the activity or numbers of immune cells or cytokines, whose job it is to attack invading pathogens.” When the immune system senses these microbes in the gut, it launches a response. Probiotics can also produce antibacterial compounds called bacteriocins, which directly inhibit the body’s tolerance of pathogen growth. The plain-English version: probiotics are the good bacteria that kick out the bad, and then make it harder for the bad actors to get back in the door. They help your dog digest her food, increase her absorption of nutrients and boost her immune system, too.

When it comes to optimizing the use of probiotics, Dr. Robert Boyle, a clinical lecturer with the UK’s National Institute for Health Research, suggests that they work best as preventive agents. “Once disease is established,” Boyle writes, “it is harder for [probiotics] to compete with pathogenic bacteria and processes that have already become established in the gut.” While your dog is well, get her started with a diet rich in good microflora. But where do you get it?
2. Do it yourself.
Most over-the-counter supplements include strains of several common probiotic microorganisms — Bifidobacterium bifidum, Lactobacillus acidophilus and Lactobacillus bulgaricus, for example — but the quality of these cultures varies wildly. Some nutritionists suggest buying only refrigerated supplements, since the shelved strains may be dead by the time you get them home. However, in 2009, the University of Toronto published a study that, among other things, questioned the batch-to-batch consistency in all probiotics, and found that enthusiasm for their use “has been hampered, at least in part, by concerns about precisely how the various organisms purported as probiotics mediate their beneficial effects.” In other words, there were so many products on the market, with so many different “mechanisms of action,” that questions were raised about the efficacy of these products as a whole. If you do buy supplements, it’s best to shop for whole-food, organic, refrigerated products, to check their expiration dates and to buy from companies that provide laboratory assays, or summaries of the drug potency. But are supplements your only option?

The reality is that plenty of foods contain natural probiotics. Yogurt, kefir, onions, bananas, garlic, honey, leeks, kimchi and Jerusalem artichokes all appear regularly on lists of probiotic foods. Some of these items are not ideal for dogs; for example, onions and large quantities of garlic are dangerous and should be avoided. Kimchi is too spicy. The jury is out on dairy products, yogurt included. Some literature contends that dairy causes digestive upset in dogs, but a better part of the homefeeding community includes yogurt in their dogs’ diets to great effect. Some dog guardians, including C.J. Puotinen, author of The Encyclopedia of NaturalPet Care, are so adventurous that they feed things like lacto-fermented vegetables, such as mild homemade sauerkraut or shredded carrots with ginger. (For the brave souls who wish to try offering fermented veggies, note that fennel seed is a natural remedy for flatulence.)

Ultimately, you can work in any number of ways with a supportive veterinarian to come up with a safe, nutritious regime that takes gut health, and therefore probiotics, into account. The best takeaway in your DIY probiotic diet handbook, the number-one answer that most experts agree on — in part because it has many other benefits and is easily digested — is green tripe. Sticking with foods that are easily digested by your dog (like green tripe) makes the addition of probiotics to your dog’s mealtime routine incredibly safe. That’s the good news.
3. Find a balance.
So, you mindfully begin supplementing your dog’s diet, but her coat remains dull and her energy, sluggish. What could be going on? No matter how thoughtfully we supplement, the detrimental effects of kibble riddled with carbohydrates and fillers can ruin our best auxiliary efforts. The sugars in these foods not only fail to protect your dog from harmful bacteria, they nourish the very bacteria we wish to discourage. Dr. Jeannie Thomason, cofounder (with Dr. Kim Bloomer of the American Council of Animal Naturopathy, suggests that with yeast and other harmful bacteria thriving in the gut, it’s no wonder veterinarians are seeing a rise in inflammatory bowel disease, irritable bowel syndrome, diabetes and pancreatitis. The preservatives and synthetic chemicals in low-quality food damage the tissues of the digestive tract and flood the body with toxins.

Thomason reminds us that a healthy, species-appropriate diet is the first line of defense against illness, and will often balance the gut naturally. “In nature, animals know to seek out those foods that satisfy their nutritional needs.” Shepoints to the eating patterns of free-roaming wolves. “Before eating muscle or bone, wolves feast on stomach contents, the liver, pancreas and intestines — in other words, they are gorging on enzyme-laden tissues. Wolf pups are weaned and maintained on regurgitated food, also heavily laced with digestive enzymes.”
4. Monitor your dog’s daily life.
Just as diet has a profound effect on a dog’s wellness, several factors can radically affect the extent to which probiotics are able to win the war in the dog’s GI system. For example, a dog who’s undergone antibiotic therapy needs support to recover at the microbiotic level. These therapies make no distinction between beneficial and harmful microorganisms; they destroy them all. Many experts suggest that the harmful strains, being more opportunistic, are quicker to re-colonize and exploit the body’s vulnerabilities. Travel and other environmental changes can be overwhelming, literally altering an animal’s body chemistry. Everyday stresses and the effects of a sedentary lifestyle throw off balance as well. Aging, while inevitable, can also influence the normal balance of microflora in the intestinal tract. Your dog depends on you to protect him from undue stress and thus improve his chances of long-term wellness.

So it’s true — I follow trends. I give my dog yogurt (she’s fine with it). I have offered her homemade fermented veggies (hence the fennel-seed tip). And I have even made it routine to periodically include green tripe in her menus. What we call fads today can become tomorrow’s conventional wisdom when they prove to be legitimate practices that advance our health and happiness. I now know it’s healthy to take probiotics into account. And judging from my dog’sresponse when the tripe hits the bowl, I have the happiness part covered, too.