Why Giving Your Dog Prebiotics Could Be a Big Mistake

Analysis by Dr. Karen Shaw Becker

what prebiotics do for dogs

Story at-a-glance -

  • One of many factors that affects the health of your dog’s gastrointestinal tract is the process of aging; over time, the gut becomes less efficient at absorbing nutrients and microbial diversity is reduced
  • The ultra-processed pet food industry adds a variety of gut health products to their formulas for senior dogs, including prebiotics, which are non-digestible food ingredients in the form of complex sugars
  • What many people don’t realize is that prebiotics should not be given to dogs with GI disorders (the majority of dogs today); they can only safely be given to pets with very healthy digestive tracts
  • If you feed a nutritionally optimal commercial raw diet or prepare balanced homemade meals for your otherwise healthy dog, you really shouldn’t need to add prebiotic supplements
  • Whole food sources of prebiotics that are safe for dogs in small quantities include asparagus, apples, cashews, raw garlic (¼ teaspoon of freshly chopped garlic per 15 pounds of body weight) and bananas

Not that you ever would, but if you stretched the surface area of your dog's intestines out end-to-end, astonishingly, they would cover "more than enough space for a good game of fetch," writes senior reporter Tim Wall in an article for PetfoodIndustry.com.1 And almost as impressive as the surface area of the canine gastrointestinal (GI) tract is the range of microorganisms (aka the microbiome) that live there.

All that terrain encourages a large and complex community of bacteria and other organisms to take up residence in the intestines, and the complexity lends itself to a considerable variation in microbes between species and individuals within species. It's one of the reasons that science has yet to define a "normal" or typical canine microbiome.

When a dog's microbiome becomes unbalanced, leaky gut syndrome (dysbiosis) is often the result. Leaky guts play a significant role in the digestive problems and chronic inflammation so prevalent in today's canine companions.

One of the many factors that can influence the health of your dog's GI tract and microbiome is the aging process. The gut ages right along with the rest of your dog's organs and becomes less able to absorb nutrients. It also loses both microbial diversity and "good bugs" — beneficial bacteria. Both these situations can contribute to a leaky gut.

As you might guess, the diet dogs are fed has a tremendous impact on how well their guts are able to control inflammation and absorb vital nutrients throughout their lives.

How Big Pet Food Addresses Gut Health Issues in Aging Dogs

Ultra-processed pet food formulators have a wide range of gut health products such as probiotics, enzymes, prebiotics and plant extracts at their disposal.

While I'm thankful the pet food industry recognizes the benefits of phytonutrients and nutraceuticals, the often poor-quality raw materials used in 95% of ultra-processed pet food, coupled with the manufacturing processes necessary to produce kibble and canned products with a long shelf life, results in diets that are far from optimally nutritious. Even with a splash of added turmeric or in this case, prebiotics.

It's important to understand that when dogs are fed a lifetime of whole, fresh, nutritionally optimal foods, in many cases their digestive tracts continue to function normally through old age without the need for continuous supplementation with gut health products.

Adding a few gut health supplements to ultra-processed diets for senior dogs is the equivalent of putting lipstick on a pig (no offense to pigs) or applying a coat of paint to cover cracks in the walls of a house sitting on a crumbling foundation. And in the case of prebiotic supplements, it can make a bad situation worse (more about this shortly).

Prebiotics Feed the Growth of Intestinal Bacteria

The ultra-processed pet food industry isn't the only one interested in prebiotics —lots of pet parents come to this site searching for information on them as well. In a nutshell, prebiotics feed the growth of intestinal bacteria and come in food or supplement form. Prebiotic supplements added to pet food lack the whole food matrix, so they are only complex sugars, including:

  • Fructooligosaccharides (FOS), which is produced from the natural fermentation of sugar cane
  • Inulin
  • Oligofructose, a breakdown product of inulin
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Prebiotic Supplements and Dogs With SIBO

What many people don't realize is that unlike probiotics, prebiotic supplements aren't right for every pet. Marketing claims often position them as feeding only friendly bacteria in the digestive tract, but studies show this isn't the case — prebiotics nourish unhealthy bacteria, including Klebsiella overgrowth and yeast as well.

For a dog with a very healthy digestive tract, prebiotic supplements probably won't do any harm. But many pets today have GI conditions like inflammatory bowel disease (IBD), leaky gut, small intestinal bacterial overgrowth (SIBO), and other issues.

This means the good-to-bad bacteria ratio in the GI tract is out of balance, and we definitely don't want to feed potentially pathogenic bacteria or yeast with large amounts of prebiotics. Pets with yeasty guts have a significant worsening of their condition when fed prebiotics, because sugar feeds yeast, and prebiotics are complex sugars.

In my opinion, however, if you feed a balanced, commercial raw diet or prepare balanced homemade meals for your otherwise healthy pet and rotate recipes frequently, you don't need to add prebiotic supplements unless your integrative veterinarian specifically recommends them for some reason.

5 Whole Food Sources of Prebiotics

While all pets benefit from whole foods containing prebiotic fibers, not all benefit from prebiotic supplements. The very best way for your dog to get all the dietary nutrients her body requires, including prebiotics, is in fresh whole foods offered as a part of a nutritionally optimal, species-specific diet.

It's important to note that while all prebiotics are fiber, not all fiber has a prebiotic effect on friendly bacteria.2 To be classified as a prebiotic the fiber must:

  • Resist gastric acidity
  • Resist absorption in the upper GI tract
  • Be fermented by intestinal flora
  • Stimulate the growth or activity of beneficial bacteria (and not promote the bad guys)

Prebiotic foods contain the fibers probiotics utilize in a matrix of other nutrients and phytochemicals and can be very beneficial for your pets. Great prebiotic foods you can share with your pets include:

  1. Jerusalem artichokes (also called Sunchokes) — These amazing prebiotic superfoods can be sliced or cubed and make amazing training treats.
  2. Dandelion and arugula greens — It's fine to harvest dandelions from your yard, just make sure they're spray-free.
  3. Jicama — Another great option to cube and treat.
  4. Okra
  5. Asparagus — Asparagus is also an excellent source of vitamin K, A, B1, B2, C, and E, along with folate, iron, copper, fiber, manganese, and potassium.
  6. Apples — Apples also contain powerful antioxidants and vitamin C. Serve apple slices to your dog, but never the core or seeds.
  7. Bananas — In fact, green bananas boast of some of the best resistant starch3 and pectin that promotes healthy intestinal wellbeing. Here's a nutrient-packed bite-sized snack you can prepare for your pets using green bananas. I call them frozen basil banana towers:


  • Banana
  • Fresh basil
  • Ground free-range turkey or chicken, fresh


  1. Slice the banana
  2. Place a fresh basil leaf on each slice
  3. Top with a small ground turkey or chicken meatball
  4. Freeze for 3 hours on a cookie sheet or freezer-safe pan
banana basil tower

All of these prebiotic foods contain inulin and fructooligosaccharides (FOS) in a whole food matrix, which includes other types of fiber and nutrients that act as fertilizers for the good bacteria in your pet's gut without the risk of fostering SIBO, as prebiotic supplements can.

When bacteria ferment prebiotic foods in the large intestine, short-chain fatty acids (SCFAs) are produced. SCFAs provide a number of benefits to your pet's gastrointestinal tract. They provide cells with energy, keep things moving through the intestines, and reduce both inflammation and overgrowth of potentially pathogenic bacteria.