Fermented Foods for Dogs: Kefir, Bone Broth, and the Gut Microbiome

Quick answer: Several fermented foods are safe and beneficial for dogs in small amounts — plain kefir (dairy or coconut), unseasoned bone broth with added fermented vegetables, and raw fermented goat's milk are the most practical options. They supply live cultures, short-chain fatty acids, and easily absorbed minerals that support the gut microbiome. Portions matter: start small, watch for loose stools, and check with your veterinarian before adding anything new.

The raw and whole-food feeding community has long championed fermented foods, and the science of the canine gut microbiome is starting to catch up. As a daily postbiotic and probiotic supplement brand, we at Plentum spend a lot of time with the research — so let's look clearly at what the evidence supports, what it doesn't, and how fermented foods can fit alongside (not replace) a complete gut-health routine.

If you're new to the topic, a quick primer on how the dog gut microbiome works will give helpful context before we dive in.

Why the Gut Microbiome Is the Starting Point

A dog's gastrointestinal tract hosts trillions of microorganisms — bacteria, fungi, archaea, and viruses — collectively called the gut microbiome. When that community is diverse and balanced, it supports digestion, immune regulation, skin barrier function, and even mood via the gut-brain axis. When it's out of balance — a state called dysbiosis — you may start to notice signs of poor gut health like intermittent loose stools, excessive gas, dull coat, or itchiness.

Fermented foods are interesting because they deliver three things simultaneously: live microbial cultures (probiotics), nutrients that feed those microbes (prebiotics), and small metabolic byproducts produced during fermentation (postbiotics). That combination is rare in a single food source. The caveat is that concentration and consistency vary widely between batches and brands — which is why fermented foods work best as a complement to a structured supplement routine rather than as a standalone strategy.

What Counts as a Fermented Food for Dogs?

Fermentation is a metabolic process in which microorganisms — mainly bacteria and yeasts — break down sugars into acids, gases, or alcohol. For dogs, the safest and most studied fermented foods fall into a few categories:

• Plain kefir (dairy) — cow's milk or goat's milk kefir, no added flavors or sweeteners
• Coconut kefir — dairy-free option made from coconut water or coconut milk
• Raw fermented goat's milk — lower in lactose than cow's milk; widely used in raw-feeding communities
• Unseasoned fermented vegetables — small amounts of plain sauerkraut (no onion, no garlic, no added salt above trace amounts) or fermented carrot
• Bone broth with probiotic cultures — some commercial bone broths are specifically fermented or enriched with live cultures

Foods to avoid: kombucha (can contain alcohol and excess sugar), yogurts with xylitol or artificial sweeteners, pickles or fermented foods preserved with high-sodium brine, kimchi (typically contains garlic and onion, both toxic to dogs), and any fermented beverages with alcohol content above trace levels.

Kefir for Dogs: What the Evidence Says

Kefir is a fermented dairy drink produced by kefir grains — complex communities of lactic acid bacteria and yeasts. It typically contains Lactobacillus, Lactococcus, and Leuconostoc species alongside beneficial yeasts like Saccharomyces cerevisiae. The fermentation process also breaks down most of the lactose, making kefir far easier for lactose-sensitive dogs to digest than plain milk.

From a microbiome standpoint, the lactic acid bacteria in kefir produce short-chain fatty acids (SCFAs) — butyrate, propionate, and acetate — that serve as fuel for colonocytes (the cells lining the colon) and help maintain the integrity of the intestinal barrier. Fermentation-derived metabolites have been studied for their effects on the canine microbiome; for more on oral and breath-related applications, see our guide to postbiotics for dogs.

Kefir portion guidance

• Small dogs (under 10 kg): 1 teaspoon per day, mixed into food
• Medium dogs (10–25 kg): 1–2 tablespoons per day
• Large dogs (25 kg+): 2–3 tablespoons per day

Start at the lower end for at least one week. If stools remain firm and your dog shows no digestive upset, you can move to the full portion. Introduce kefir every other day for the first two weeks if your dog has a sensitive stomach. Dogs with a history of pancreatitis should use low-fat or coconut kefir and only with veterinary guidance, since full-fat dairy can stress the pancreas.

Bone Broth: Fermented vs. Standard

Plain, unseasoned bone broth has become a staple in the raw and whole-food feeding world — and for good reason. Slow-simmered bones release collagen, glycine, proline, and minerals like calcium, magnesium, and phosphorus in a highly bioavailable form. Glycine in particular supports glutathione synthesis (the body's master antioxidant) and may help maintain gut lining integrity.

Standard bone broth is not fermented — it's heat-extracted. Fermented bone broth goes one step further: after simmering, cultures of lactic acid bacteria are added and allowed to ferment the broth, lowering pH, increasing SCFA content, and adding live microorganisms. The result is a product with both the structural benefits of collagen and the microbial benefits of fermentation.

What to look for in a commercial bone broth

• No onion, garlic, leeks, or chives (all toxic to dogs)
• Low sodium (ideally under 100 mg per serving for dogs)
• No added thickeners like carrageenan or guar gum in large amounts
• If marketed as "fermented," look for a live culture count or a "contains active cultures" statement

Bone broth is best used as a food topper or as a hydration aid for picky eaters and recovering dogs. It is not a meal replacement. Dogs recovering from antibiotics may find bone broth especially soothing — more on that in our guide to rebuilding gut health after antibiotics.

Fermented Vegetables: Small Amounts, Big Caveats

Sauerkraut — fermented cabbage — is one of the oldest fermented foods on record. The fermentation process enriches it with Lactobacillus plantarum and other beneficial bacteria, B vitamins, and vitamin C. In small amounts, plain sauerkraut can add a modest dose of live cultures to a dog's meal.

The key word is plain. Commercial sauerkraut is usually brined with significant amounts of salt — which dogs do not need in excess. Look for a raw, refrigerated, unpasteurized sauerkraut with one or two ingredients (cabbage, salt) and rinse it briefly before serving to reduce sodium. Start with half a teaspoon for a medium dog and watch for gas — cruciferous vegetables can cause bloating in some dogs, especially those with sensitive digestive systems.

Fermented carrots and fermented beets are gentler alternatives for dogs prone to gas from cabbage. Both ferment well in a simple brine and provide a broader range of plant fibers (prebiotics) that feed beneficial gut bacteria alongside the probiotic cultures they carry. Understanding the relationship between these two categories is worth a read in our overview of prebiotics vs. probiotics for dogs.

How Fermented Foods Interact With the Microbiome

The mechanism is layered. Live cultures from fermented foods colonize the gut transiently — most do not become permanent residents, but their passage still matters. As they travel through, they:

• Compete with pathogenic bacteria for adhesion sites on the gut wall
• Produce bacteriocins — small antimicrobial proteins — that can suppress harmful species
• Stimulate secretory IgA production, a key component of mucosal immunity
• Leave behind postbiotic metabolites (SCFAs, peptides, organic acids) that benefit the resident microbial community

This last point is why postbiotics are generating so much research interest right now. You can read more about the science in our deep-dive on the gentle power of canine postbiotics. Fermented foods produce postbiotics naturally during the fermentation process — which is part of why whole fermented foods have effects that can't be fully replicated by a heat-killed probiotic alone.

That said, fermented foods are an inconsistent delivery vehicle. Culture counts aren't standardized, and pasteurized commercial products may have no live cultures at all. For predictable, dose-controlled support, a daily postbiotic supplement fills the gap that whole foods leave.

Fermented Foods vs. Probiotic Supplements: Not an Either/Or

A question we hear often: "If I'm feeding kefir, do I still need a probiotic supplement?" The honest answer is: they do different things, and both can have a role.

The whole-food and supplement approaches are complementary. Fermented foods supply broad nutritional diversity; a supplement like Plentum supplies specific, evidence-backed strains and postbiotic metabolites at a reliable dose every day. For a comparison of how structured supplements stack up, see our 2026 comparison of top dog probiotics.

For dogs with chronic gut challenges — such as inflammatory bowel disease — the combination of dietary fermented foods and targeted supplementation is worth discussing with your veterinarian. Our article on IBD in dogs covers the diet–microbiome connection in more detail.

Practical Tips for Getting Started

A few principles that make fermented food introduction smoother:

• One new food at a time. If you introduce kefir and sauerkraut simultaneously, you won't know which one caused a reaction if something goes wrong.
• Cold is better. Refrigerated, unpasteurized products retain the most live cultures. Heat destroys them.
• Consistency matters more than quantity. A teaspoon of kefir daily for a month does more than a tablespoon randomly.
• Watch stool quality. Slightly looser stools in the first few days are normal as the microbiome adjusts. Persistent diarrhea, vomiting, or lethargy — stop and talk to your vet.
• Puppies and senior dogs: go slower. Developing and aging immune systems can be more reactive. Half portions, more gradual introduction.
• Immunocompromised dogs: vet first. Dogs on immunosuppressive medications should only receive fermented foods under veterinary supervision, as live organisms carry a small risk in severely compromised animals.

Frequently asked questions

Can dogs eat kefir every day?

Yes, plain unsweetened kefir can be part of a dog's daily routine in appropriate amounts. Most dogs tolerate it well, and the regular supply of live cultures and fermentation-derived metabolites may offer ongoing support to the gut microbiome. Start small (a teaspoon for small dogs, up to 2–3 tablespoons for large dogs), confirm your dog tolerates it well over one to two weeks, then continue as a daily food topper. Dogs that are lactose-intolerant should try coconut kefir as an alternative, since even dairy kefir's low lactose content can cause loose stools in very sensitive animals.

Is bone broth a probiotic food?

Standard bone broth is not probiotic — it's heat-processed, which kills any microorganisms present. It is, however, a good source of collagen peptides, glycine, and minerals that support the gut lining. Fermented bone broth, a product that has had live cultures added after simmering, does contain active bacteria. If you're looking for the probiotic benefit, check the label for a live culture statement, or pair regular bone broth with a separate daily probiotic or postbiotic supplement.

What fermented foods should I never give my dog?

Avoid kombucha (alcohol and sugar), any yogurt or kefir containing xylitol (toxic to dogs), kimchi and most commercial pickles (garlic, onion, excessive salt), sourdough bread (too high in gluten and carbohydrates for meaningful benefit), and any fermented alcoholic beverages. Also avoid highly salted brines — many store-bought fermented vegetables carry more sodium than a dog needs in a day. When in doubt, "plain and single-ingredient" is the safest starting point.

How do fermented foods compare to a probiotic supplement?

They're complementary rather than interchangeable. Fermented foods supply broad nutritional diversity — live cultures, vitamins, minerals, and natural postbiotic metabolites — but culture counts are inconsistent and strain identity is usually unknown. A quality probiotic or gut-support supplement provides identified, stable strains at a reliable dose. For dogs that would benefit from predictable, targeted microbiome support, a daily supplement fills the consistency gap that whole foods leave open.

Can fermented foods help with skin and allergy symptoms?

The gut and the immune system are closely linked — roughly 70% of a dog's immune tissue resides in and around the gut wall. A well-supported microbiome may therefore contribute to how the immune system regulates its response to environmental triggers. The connection between gut health and skin is discussed further in our article on probiotics and skin allergies. Fermented foods are one piece of a broader approach; talk to your veterinarian if your dog has significant or worsening allergy symptoms, as underlying causes need proper diagnosis.