You know before you get downstairs.

There's a way he stands near the back door that tells you how the morning is going to go. And you've built a whole week around it — the food you don't change, the biscuits you've stopped giving, the walk you take near home just in case.

Look at what you've already done. You switched the food, then switched it back. You rotated proteins one at a time and wrote down what happened. You did the boiled chicken and rice, and it worked, until real food came back. You bought the probiotic, then a different probiotic. There's a half-used bag in the cupboard that cost more than your own groceries.

And every time you get a good week, you can't tell whether it was the thing you changed or just a good week.

Here's the part nobody mentions in the aisle: almost everything you tried was working on what goes into his gut. Not on the gut itself.

One owner described the loop like this — every time the dry food went back in the bowl, they were straight back to square one. If that's familiar, it isn't a discipline problem and it isn't your judgement. You've been changing the contents of a room while nobody looked at the walls.

His gut isn't a container. It's a living surface — the busiest one in his body.

• You have a food you don't dare change, and you've stopped reading new ones
• You've rotated proteins one at a time and kept notes on what happened
• There's a part-used probiotic in the cupboard you're not sure did anything
• You plan walks around where the nearest bit of grass is
• You've done the boiled chicken and rice more times than you'd admit
• You read the panel on every bag now, in the shop, before it goes in the trolley
• You can't tell any more whether a good week was something you did or just luck

If three or more of those landed, read this part slowly.

The lining of your dog's gut is not a wall. It's a sheet of living cells one layer thick, sealed together by proteins that keep the gaps between them shut [1] — and it replaces itself constantly. It is among the fastest-renewing surfaces in the body.

Rebuilding costs energy. Cell renewal is one of the most energy-hungry jobs any tissue does, and the cells doing it draw on the same power supply as the rest of him — one that leans on a helper molecule called NAD+, which naturally declines with age.

Sitting on that surface is the second half: the bacteria living on it, a community that shifts with age and diet and changes what the surface can do.

So two things are in play, and the shelf only ever sold you one. A probiotic adds bacteria. Nothing in that bag was working on the surface those bacteria live on, or on the energy it needs to keep rebuilding. That's why the good weeks never held.

One thing worth saying plainly: not every stomach change in a dog is ordinary. Some are medical conditions that look similar from the outside and need a vet, not a supplement. If it came on fast, if there's blood, or if he isn't himself, get him seen first.

Add it up honestly. The prescription bag. The two probiotics. The enzyme powder. The month of gently cooked food that arrived in a cold box. Most owners reading this have spent several hundred finding out what doesn't hold.

And somewhere in there you decided the problem was you. You didn't stick with it long enough. You changed two things at once.

Almost none of that is true, and there are two plainer explanations.

First: you were adding tenants, not repairing the building. Bacteria don't live in mid-air. They live on a surface that has to keep rebuilding itself, and no amount of new bacteria changes what that surface can do.

Second: a change in that community is not the same as a result. Even when something genuinely shifts which bacteria are present, that is a change in the mix — not a promise about how your dog will feel. Anyone telling you otherwise is selling past their evidence.

Underneath both sits what nobody in that aisle mentions. Renewal runs on energy. The cells rebuilding that lining are packed with mitochondria — tiny power plants — and those run on NAD+, which drops as a dog gets older.

That pathway is now being tested in dogs directly: a placebo-controlled trial in senior dogs used an NAD+ precursor and reported a measurable difference on owner-assessed scores [2]. Different product, and the endpoint was cognition — it proves nothing about his stomach. What it shows is that the pathway is worth taking seriously in a dog.

Pawprint Protocol wasn't built as a gut product. It was built around cellular energy — and the gut lining is where that matters most, because nothing else in the body rebuilds itself so relentlessly.

The lead active is NMN, the building block cells use to make NAD+, and the one active here with dog research behind it. The most relevant piece is about the gut: applied to canine intestinal cells — dog gut-lining cells, not a rodent's — NMN raised ATP and changed how those cells proliferate [3]. Proliferation is the technical word for the rebuild.

Be clear what that is. Cells in a dish, not dogs in a trial. Mechanism, not outcome. But it is dog tissue, not a mouse standing in for one.

Resveratrol rides along with it. Most of what a dog swallows never really leaves the gut — everywhere else that's the complaint, here it's the point. It isn't a passenger that missed its stop. This was the stop. Gut bacteria convert it into the compounds carrying much of its activity [4], and in dogs fed it daily for 35 days the make-up of the gut community shifted [5].

The counterweight, because you should hear it from us: a related precursor moved that community in rats and mice, and changed nothing detectable in people [6]. Species don't always translate.

Then delivery — a liposomal liquid, built to be absorbed rather than just swallowed.

Every shelf in the digestion aisle sells the same idea in a different bag: add more bacteria. If that had solved this for your dog, you wouldn't have read this far.

Pawprint Protocol works one level underneath — on the cellular energy the gut's own lining draws on to keep rebuilding. A few drops on his food, once a day.

Four actives, each with a job:

• NMN: The building block cells use to make NAD+, the fuel-helper molecule that naturally declines with age. The hero here, and the one with dog research behind it — including work in canine intestinal cells [3].
• NAD+: Part of the same pathway, supporting the cellular energy renewal depends on.
• Resveratrol: A plant compound that largely stays in the gut, where its own metabolites are made by the bacteria living there [4].
• CoQ10: Sits inside the mitochondria — the power plants in every cell — where energy gets made.

All four in a liposomal liquid, because an ingredient that doesn't get absorbed is a line on a label, not a dose.

✔ Supports a healthy gut barrier
✔ Supports a normal, healthy microbiome
✔ Supports the cellular energy that naturally declines with age
✔ Works alongside any food — kibble, raw, fresh, gently cooked or home-made

Not a probiotic, and it contains no live cultures. Made for dogs 7 and up. Individual results may vary.

Nobody should promise you a timeline on a stomach, and we won't. What owners describe is less a moment than a slow loosening of the rules they'd built. Here's the pattern we hear most often, in the order we usually hear it. Individual results may vary.

Almost nothing to see, and that's normal. What owners mention at this stage is the dropper itself — that it went into his food and he ate the food, which after a year of hiding things in cheese is its own small relief.

This is usually where the mental load lifts. Owners tell us the morning check stops being the first thing they think about, and the walk stops being planned around contingencies. Not a transformation — a week that needs less managing than the last.

Around here owners mention the rules they'd made, and how many they've quietly stopped following. The list of foods that feel risky gets shorter. Good weeks stop feeling like luck and start being most weeks.

For a lot of families this is the one they register: the notes app where they logged every meal hasn't been opened in a month, and they can't say when they stopped.

Three months in, the job changes from noticing to keeping. That lining rebuilds every day for the rest of his life and NAD+ keeps declining with age, so the dogs who hold their ground are the ones who stay on it.

This supports how his body maintains itself. It doesn't treat anything. Individual results may vary.

A sensitive stomach was never really about the food in the bowl.

Every switch, every rotation, every bag was aimed at the contents. Underneath all of it was a living surface, rebuilding itself daily on an energy supply that quietly drops as a dog gets older — and nothing in that aisle was made for it.

That part is supportable. Not fixed, not cured — supported, daily. It starts with a few drops on dinner tonight.

Reviews are unedited excerpts from verified Trustpilot reviews of Pawprint Lab and describe those owners' own experiences, not results on this angle. Individual results may vary.

[1] Lobo de Sá, F.D. et al. Resveratrol Prevents Campylobacter jejuni-Induced Leaky Gut by Restoring Occludin and Claudin-5 in the Paracellular Leak Pathway. Frontiers in Pharmacology, 2021;12:640572. PMID 33935732. — Cell line and mouse model; no canine data.

[2] Simon, K.E. et al. A Randomized, Controlled Clinical Trial Demonstrates Improved Owner-Assessed Cognitive Function in Senior Dogs Receiving a Senolytic and NAD+ Precursor Combination. Scientific Reports, 2024;14:12399. PMID 38811634. — A different product, on cognition. Category evidence only.

[3] Guo, X. et al. Nicotinamide Mononucleotide Modulates Endothelin-1 via NR4A1 and Histone Modifications in Canine Intestinal Epithelial Cells. Animals (Basel), 2026;16(4):591. PMID 41751051. — Canine cells in vitro, single-arm. Mechanistic; not an outcome in living dogs.

[4] Li, F. et al. Gut Microbiota-Derived Resveratrol Metabolites, Dihydroresveratrol and Lunularin, Significantly Contribute to the Biological Activities of Resveratrol. Frontiers in Nutrition, 2022;9:912591. PMID 35634412. — Mouse and in-vitro study.

[5] Bian, Z. et al. Resveratrol Ameliorates Chronic Stress in Kennel Dogs and Mice by Regulating Gut Microbiome and Metabolome Related to Tryptophan Metabolism. Antioxidants (Basel), 2025;14(2):195. PMID 40002382. — Resveratrol alone, in a form and amount unlike this formula. Barrier findings are from its mouse arm.

[6] Peluso, A.A. et al. Oral Supplementation of Nicotinamide Riboside Alters Intestinal Microbial Composition in Rats and Mice, but Not Humans. npj Aging, 2023;9:7. PMID 37012386. — A different precursor. The negative result.