He used to hear the car door from the back bedroom.

That’s the part that stays with you. Not a limp, not a bad day — just the door going, and him not coming. You said his name twice from the hallway last week before he lifted his head.

Then the mornings. He’s up, he eats, he’s fine. But there’s a stretch of twenty minutes now where he moves like the day hasn’t started yet. By mid-morning he’s himself again.

And the toy. Not that he can’t. He just doesn’t bother the way he did.

You’ve started working around all of it without ever deciding to. The main walk moved to whichever part of the day is easier. You wait a beat before asking him to do anything in the first hour. You stopped throwing the ball, because he stopped bringing it back and it felt unkind to keep asking.

Here’s what owners get wrong about that list. It isn’t any one item on it.

It’s that there are four.

A sore hip explains one. A bad night explains one. Nothing explains four at once — the sleep, the slow start, the hearing, the interest — unless something underneath all four is running short.

That’s the detail saying this isn’t simply age arriving. Age doesn’t pick four unrelated things on the same schedule. A shortage does.

• You wait a beat before asking him to do anything in the first hour of the day
• You’ve moved the main walk to whichever part of the day is easier on him
• You say his name twice now, and you’ve stopped noticing that you do
• You stopped throwing the ball because he stopped bringing it back
• You lift him into the car for trips you used to just open the door for
• You’ve caught yourself calling him an old man out loud, fondly
• You already tried a senior chew or a joint powder, and none of the four changed

If three or more of those landed, the useful question isn’t how old he is. It’s what all of them have in common.

Here’s the part the senior-dog shelf never explains. Every cell in his body runs on a fuel called NAD+. It isn’t stored up in bulk — it gets rebuilt constantly, all day, in a loop biologists call the salvage pathway. Spend some, rebuild some. That loop is running right now in his brain, his muscles, his heart and his gut.

Two things happen to it as a dog ages, and they pull the same way.

The rebuilding slows. Reviews of the aging literature describe NAD+ availability falling as animals get older — though how far, and in which tissue, is still argued over [1]. And the spending speeds up: in studies on aging mice, an enzyme called CD38 climbs with age and drags NAD+ down with it [2]. That part hasn’t been studied in dogs yet. Meanwhile the mitochondria that spend NAD+ lose output as they age [3].

Picture one sink with two taps. One fills it, the other empties it. With age the filling tap slows down, and the emptying one opens wider.

For years the sink still looks full, because organs carry more capacity than they need — and that spare capacity erodes quietly long before anything shows on the outside. What you’re seeing in four places isn’t four problems. It’s the level finally dropping far enough to notice.

One thing matters more than everything above. Not every dog who slows down is short on cellular fuel. Some are telling you about something else entirely, and those need a vet, not a supplement. If it came on fast, or it’s worse on one side, or his drinking or weight has changed, get him seen first.

Most owners reading this have already spent money here. A tub of senior chews. A joint powder. Maybe a calming supplement, because one of the four looked like it might be nerves. Two or three brands over a couple of years, each bought on a real hope.

And when nothing on the list moved, most people file it under their own judgement. You picked the wrong one. You didn’t give it long enough. You should have read more labels.

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

First: the category is aimed somewhere else. Walk the senior aisle and count what’s actually on offer. Joints, hips, calm, coat. Real products for real problems — and every one of them aimed at a single system. You were describing four at once. No product built for one of them was ever going to answer that.

Second: what you were buying wasn’t the shortage. Glucosamine is building material for cartilage. It does an honest job and it has nothing to do with the fuel loop. You can supply it perfectly and change nothing about how much a cell in his brain or his heart can produce on a Tuesday evening.

Underneath both sits the same thing. The systems on your list don’t share a joint or a nerve. What they share is that every cell in all four is drawing on the same rebuilt fuel — and when the loop that rebuilds it falls behind, the shortfall doesn’t stay politely in one place.

Pawprint Protocol was built by owners who had already been down the senior aisle and wanted to know what sat underneath it.

Working with their consulting veterinarian, they built a daily liquid around one job: supply the raw material his body uses to rebuild that fuel, in a form that survives the trip.

The lead active is NMN — the direct building block for NAD+, and the one active here with published dog work behind it. Beagles given oral NMN for fourteen days tolerated it well, and nicotinamide-pathway markers rose in their blood, which says the pathway is active in a dog, not only in a mouse [4]. Be precise about it, though: that was a safety study, and its NAD+ tissue readings came from mice, not the dogs.

Just as precise about the bottle: it supplies a precursor, raw material for the loop. It doesn’t post finished NAD+ into a cell; the body doesn’t work that way.

And the objection worth raising before you do: none of this was tested on this bottle. The strongest dog-side evidence is a randomised, placebo-controlled trial in seventy senior dogs at a veterinary school — on a different product built around an NAD+ precursor [5]. That proves nothing about Pawprint Protocol. It shows the pathway is worth taking seriously in dogs, not just mice. The human reviews are honest about the same gap: promising in the lab, limited so far in human trials, and rodent results that don’t transfer straightforwardly [6].

Then delivery. Pawprint Protocol is a liposomal liquid, not a pill or a chew — each active wrapped so it survives the stomach. Built to be absorbed, not just swallowed.

A few drops on the food he already eats. No pill pockets, no cheese. Individual results may vary.

The senior shelf is a wall of single answers: one for the joints, one for the nerves, one for the coat. If any one of them had been the answer for your dog, the other three things on your list would still be there.

Pawprint Protocol works underneath all of them — at the fuel loop every cell in every one of those systems draws on. A few drops on his food, once a day.

Four actives, each with a job:

• NMN: the direct building block cells use to rebuild NAD+, the fuel that naturally declines with age. The lead active, and the one with published dog work behind it.
• NAD+: feeds the same salvage pathway from the other end, supporting the cellular energy every system on your list runs on.
• Resveratrol: a plant compound studied for its part in the signalling around that pathway.
• CoQ10: sits inside the mitochondria, where the fuel gets spent.

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

✔ Supports healthy cellular aging
✔ Supports the cellular energy his body runs on
✔ Built to be absorbed, not just swallowed
✔ Works alongside any food — kibble, raw, fresh or home-cooked

Made in the USA, third-party lab tested. Made for dogs 7 and up. Individual results may vary.

You don’t need three months to see whether anything is happening. Most owners tell us the first changes show up in days to weeks — and on this angle they rarely arrive as one big moment. They arrive as items quietly coming off the list you’d stopped counting. Individual results may vary.

Small, and easy to miss if you’re waiting for a transformation. That twenty-minute stretch where the day hasn’t started yet starts shrinking. He’s up and into it sooner. One owner told us what she noticed first wasn’t the mornings at all — it was him beating her to the kitchen, which he hadn’t done in a year. Individual results may vary.

This is usually where the second call stops being necessary. You say his name once. Owners often mention the small arrivals here — him in the kitchen doorway when the bag rustles, him at the top of the hall when the car pulls in.

Owners tend to mention the toy around here. Not fetch as it was at three — just him picking it up again, carrying it about, dropping it hopefully near someone. Good days stop being events and start being most days.

For most families this is the one they actually notice: the waiting-a-beat, the easier time of day, the not-asking — those stopped being the routine, and nobody can say quite when.

Three months in, the job changes from noticing to keeping. NAD+ keeps declining with age and the spending doesn’t pause, so the dogs who hold their ground are the ones who stay on it.

And the earlier a dog starts, the more spare capacity there is to support. Individual results may vary.

The sleeping wasn’t the beginning of this. It was one of the first parts you could see.

Everything on your list — the slow first hour, the name said twice, the ball left where it landed — was the same shortage surfacing in four places at once. He didn’t stop caring. The cells doing the work ran short of the fuel it costs.

That is supportable, and it starts with a few drops on dinner tonight. Individual results may vary.

Reviews are unedited excerpts from verified Trustpilot reviews of Pawprint Lab. Individual results may vary.

[1] Peluso, A. et al. Age-Dependent Decline of NAD+ — Universal Truth or Confounded Consensus? Nutrients, 2021. Review. PMID 35010977.

[2] Camacho-Pereira, J. et al. CD38 Dictates Age-Related NAD Decline and Mitochondrial Dysfunction Through an SIRT3-Dependent Mechanism. Cell Metabolism, 2016. Mouse study. PMID 27304511.

[3] Chistiakov, D.A. et al. Mitochondrial Aging and Age-Related Dysfunction of Mitochondria. BioMed Research International, 2014. Review. PMID 24818134.

[4] You, Y. et al. Subacute Toxicity Study of Nicotinamide Mononucleotide via Oral Administration. Frontiers in Pharmacology, 2020. Safety study in beagles; NAD+ measured in mice, not dogs. PMID 33384603.

[5] Simon, K.E. et al. A randomized, controlled clinical trial… senolytic and NAD+ precursor combination in senior dogs. Scientific Reports, 2024. Different product. PMID 38811634.

[6] Vinten, K.T. et al. NAD+ precursor supplementation in human ageing. Nature Metabolism, 2025. Review; human, not dogs; reports limited efficacy in human trials. PMID 41083806.