He still comes to the door when he hears the leash.

That’s the part that doesn’t fit. You know the walk. Out the front, left at the corner, down past the school, loop back. Two years ago that was the short version. Now you turn around at the school, and some evenings before it.

He starts the same as always — nose up, pulling a little, ears forward. Then somewhere in the middle the pulling stops. He falls in behind you. And at roughly the same corner, he sits down and looks up the street.

You’ve started planning around it. The short loop on work nights. The car for anything past the park. You call it his pace now, and you slow to match it without thinking.

Here’s the shape owners describe over and over: he starts out excited, then halfway through he slows right down and wants to stop.

Read that again. He still wants to go. Something runs out on the way.

That’s the detail saying this isn’t simply age catching up. A dog who had lost interest wouldn’t come to the door. A dog who hurt would refuse from the start. This one commits, then fades — almost always in the middle, rarely at the beginning.

Something is being spent faster than it’s replaced. And it isn’t in his legs.

• You’ve shortened the usual route, and you never actually decided to
• He starts the walk pulling and finishes it behind you
• You take the car now for distances you used to walk
• He sits down at roughly the same point every time and waits
• You’ve started calling it “his pace” instead of a slow day
• He still comes to the door for the leash — the wanting hasn’t changed
• You already tried a joint chew or a calming powder, and the distance didn’t come back

If three or more of those landed, the useful question isn’t how old he is. It’s what he’s running out of.

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 in bulk — it gets rebuilt constantly, all day, through what biologists call the salvage pathway. Spend some, rebuild some. That loop is running right now in every muscle he’s using.

Two things happen to it as a dog ages. The rebuild slows — reviews of the aging literature describe NAD+ availability falling as animals get older [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 mitochondria — the parts of the cell that turn fuel into movement — lose output as they age [3].

The result is a ceiling. Not on how much he wants to do. On how much energy his cells can produce while he does it.

The tank isn’t smaller. The refill got slower.

That is why it shows up halfway and not at the start. He begins on what’s already there. The trouble is what’s behind it.

One thing matters more than all of the above. Not every dog who slows down is short on cellular fuel. Some are telling you about something else, and those need a vet, not a supplement. If it came on fast, or he’s stiff on one side, get him seen first.

Most owners reading this have already spent money here. A bag of hip-and-joint chews. A calming powder, because maybe he was just uneasy about the road. Two or three brands over a couple of years, each bought on a real hope.

And when the distance didn’t come back, 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. Joints, hips, calm. Real products for real problems — and none built for the thing you’re describing. A cushioned joint does not make more energy. If he could physically manage the distance and stopped anyway, joint comfort was never the lever.

Second: what you were buying wasn’t the shortage. Glucosamine is building material for cartilage. It has nothing to do with the fuel loop. You can supply it perfectly and change nothing about how much energy a muscle cell turns out on a Tuesday evening.

Underneath both sits the same thing. Muscle cells are packed with mitochondria — thousands of tiny power plants each. They run on NAD+, handing electrons down a chain to release the energy a stride costs. When NAD+ supply falls behind, the chain has less to work with. The wanting stays. The output drops.

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

Working with their consulting veterinarian, they built a daily liquid around one job: feed the loop. Give cells the raw material they use to rebuild NAD+, 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 genuinely active in a dog and not only a mouse [4]. Be precise about that study, though: it was a safety study, and its NAD+ tissue readings came from mice, not the dogs.

Then CoQ10, the other half of the story here. NMN and NAD+ feed the pathway; CoQ10 is the mobile carrier at the Q junction — the shuttle moving electrons from one complex to the next inside the mitochondria. Feeding the loop without the carrier is half a job.

And the objection worth raising first: none of this was tested on this bottle. The strongest dog-side evidence for the pathway 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. Reviews of the human work land in the same place [6].

Use the dropper to add the recommended daily amount to your dog's food. Follow the directions on your bottle.

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 the same two promises: cushion the joint, settle the nerves. If either had been the answer for your dog, the walk would already be longer.

Pawprint Protocol works underneath both — at the cell that produces the energy every stride costs. 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.
• CoQ10: the mobile carrier at the Q junction — the shuttle moving electrons through the chain where energy is released. Co-lead here.
• NAD+: feeds the same pathway from the other end, supporting the cellular energy his working muscles draw on all day.
• Resveratrol: a plant compound studied for its part in the signalling that keeps NAD+ supply topped up.

Pawprint Protocol combines NMN, NAD+, resveratrol, and CoQ10 in an easy-to-use liquid formula for dogs.

✔ Supports the cellular energy his body runs on
✔ Supports normal stamina on daily activity
✔ Easy-to-use liquid drops
✔ 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 show up as distance. A few more houses. One less turn-around. Here’s what owners describe most often. Individual results may vary.

Small, and easy to miss if you’re waiting for a transformation. The turn-around comes a little later than it did. He’s still behind you on the way home, but he gets there without the sit-down. One owner told us what she noticed first wasn’t the walk — it was him getting up the moment she picked up the leash. Individual results may vary.

This is usually where the sit-down at the same corner shortens, then quietly stops. The old route comes back — not because you pushed for it, but because he didn’t turn. Owners often mention the pulling lasting into the second half again. Individual results may vary.

Owners tend to mention the end of the day here. He’s up for the second walk instead of settled for the night. Play restarts — the toy he’d stopped bothering with. Good days stop being events and start being most days. Individual results may vary.

For most families this is the one they actually notice: the short loop stopped being the default, and they can’t say when that happened.

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.

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

The shorter walk wasn’t the beginning of this. It was the first part you could see.

Everything before it — the pulling that stopped earlier, the evening loop you skipped, the toy left where it was — was the same shortage showing up quietly. He didn’t stop wanting the distance. His cells 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. PMID 41083806.