Gut Health — the garden within
Roughly 80% of the immune system lives in the gut. Which is why so many problems that present somewhere else — skin, mood, joints — turn out to start here.
The three axes
The gut–skin axis. Red inflamed skin, recurring hot spots, ear infections and obsessive paw-chewing are the smoke and flames of a fire happening in the gut. Standard skin treatments mask the symptom and leave the cause running.
The gut–brain axis. The microbiome steers emotional state through the vagus nerve. Imbalances are linked to behaviour problems, reactivity, thunderstorm phobia, training difficulty and mood. In older dogs, poor oral and gut microbiomes are linked to cognitive decline.
Liver and lymphatics. All blood from the GI tract filters through the liver, and the liver's ability to clear chemicals depends heavily on gut methylation. The gut's lymphatic capillaries carry fat-soluble nutrients in and fat-soluble toxins away. Stagnation in either network cascades outward.
Leaky gut, mechanically
Chronic inflammation damages the mucosal lining, and the tight junctions between cells — the gatekeepers — start pulling apart. That's hyperpermeability.
As the barrier degrades, a gut-lining protein called zonulin rises and widens the gaps. Environmental toxins, pathogens and large undigested food proteins pass straight into the bloodstream. The immune system sees those misplaced proteins as invaders and attacks.
That cascade is where chronic food sensitivities, allergies and autoimmune conditions come from.
What breaks it
Processed kibble. Cooked at high temperature multiple times. High carbohydrate feeds pathogenic bacteria, no live enzymes survive, and chemical preservatives are hard on beneficial flora.
Glyphosate. Dogs carry the highest measured glyphosate levels of any animal — averaging around 32 times more than humans. It's water-soluble and falls in rainwater globally. In the body it behaves like an antibiotic: it damages the microbiome and disrupts tight junctions. Non-GMO crops sprayed at harvest to dry them — oats, peas, chickpeas, lentils — are why grain-free foods are so often heavily exposed.
Pharmaceutical overuse. Metronidazole is routinely overprescribed for diarrhoea and can suppress microbiome diversity for months. Acid reducers lower stomach acid, so proteins never break down into harmless amino acids — which directly drives food sensitivities. NSAIDs and steroids damage the lining too.
Stress. Anxiety in the dog and in the owner triggers fight-or-flight, which halts digestion and promotes gut inflammation and permeability.
What rebuilds it
Fresh, species-appropriate food with real variety across proteins, organs and raw parts. Variety is what builds species richness.
Bone broth. Rich in collagen and gelatin, which help seal and repair damaged intestinal membrane.
Fermented raw dairy — raw goat's milk, kefir, ghee. Natural viable probiotics and yeasts, easily absorbed.
Vegetable fibre. Small amounts of pureed leafy greens, sweet potato, squash. Lactobacillus and bacteroides require plant fibre to colonise and regulate the immune system.
Warm, never cold. Food straight from the fridge dampens digestion. Serve at room or body temperature.
Well-sourced fats. From grass-fed, pasture-raised animals. Healthy raw fats don't cause pancreatitis — processed carbs, rancid fats and sugars do.
The three supplement types, and which you actually need
Probiotics — live beneficial bacteria and yeasts. Repopulate and balance so pathogens get crowded out. Use for: diet transitions, travel and stress, and during antibiotics — use Saccharomyces boulardii for that, because it's a yeast and survives the medication. Don't: run a single strain long-term. Rotation is what prevents microbiome narrowing.
Digestive enzymes — protease, amylase, lipase. Break food into absorbable nutrients. Use for: senior dogs, any dog on kibble or a cooked diet, food stagnation (bloating, gas, undigested food in stool). Don't: use blends containing bromelain in warm dogs — frequent panting, red tongue, seeking cool floors. It can worsen reflux.
Soothing / leaky gut powders — mucilaginous herbal blends. Heal the lining, tighten the junctions. Use for: acute flares of hot diarrhoea, bloody or mucusy stools, suspected leaky gut. Don't: use indefinitely. They also interfere with absorption of other nutrients and medications.
Probiotic activation — this matters
Never dump dry freeze-dried probiotic capsules onto kibble; stomach acid destroys them.
- Selection — full-fat plain yogurt, raw milk, or room-temperature bone broth
- The mix — open the capsule and stir it thoroughly in
- The wait — let it sit at room temperature for 30–60 minutes. This hydrates and wakes the bacteria
- The delivery — feed the liquid 30 minutes before the main meal, so it slips into the small intestine
Diversity, ranked
Whole foods lead. Raw goat's milk and kefir carry thousands of strains of beneficial bacteria and yeasts — far wider species richness than any lab-grown powder.
Concentrated powders are targeted therapy. Highly effective for a specific job: SIBO, post-antibiotic recovery, an active flare. Used indefinitely without rotation, they narrow the microbiome.
The one warning worth repeating
Never use slippery elm or other soothing herbs indefinitely. If a dog needs them daily to produce a normal stool, the herbs are masking something — a hidden pathogen or bacterial overgrowth. That's a signal to investigate the root cause, not to keep bandaging it.
A dog who can't hold a normal stool without herbal support has an unanswered question, not a supplement requirement.
The feeding schedule nobody mentions
Constant treating stops the gut cleaning itself. Leave 2.5 to 3 hours between meals and treats so the migrating motor complex — the gut's janitor — can sweep pathogens out of the small intestine. That's what prevents small intestinal bacterial overgrowth and the leaky gut behind it.