LongTails vs Leap Years: Which NAD+ Supplement Actually Fits Your Senior Dog?

By Tia Perry, DVM, CVCH, CERPV, CVMMP, CVFT, CTPEP, CVA, MSIVM-C, MSIVM-E, MSTCVM

✓ Medically reviewed by Tia Perry, DVM, CVCH, CERPV, CVMMP, CVFT, CTPEP, CVA, MSIVM-C, MSIVM-E, MSTCVM — August 17, 2026 For general education — not a substitute for veterinary care.

Research · August 19, 2026 · 7 min read

Two well-funded NAD+ brands are chasing the same senior-dog owner, and neither one is lying to you outright — they're just answering different questions.

Why do two supplement companies with almost nothing in common — one a powder built around collagen and nicotinamide riboside, the other a chew with a Harvard pedigree and a splashy Nature paper — keep landing in the same comparison searches?

Because owners aren’t asking “which ingredient is best.” They’re asking something closer to: my dog is graying at the muzzle, slower on stairs, still wants to play but tires faster — what actually helps, and how do I tell real signal from a good press release?

In my practice, that question usually shows up around year nine or ten, and it rarely shows up alone.

A Tuesday exam room, an eleven-year-old Lab mix named Otis. His owner had already read three blog posts before she got to me — she wanted to know if she should switch him from a joint chew to “one of the NAD+ ones.” Otis weighed 78 pounds, had lost the habit of jumping into the car without a running start, and slept later than he used to on weekday mornings. Nothing acute, nothing that screamed disease — just the slow accumulation owners describe as “he’s just getting older,” usually said with more worry in the voice than the words carry. We talked through his current joint support, his weight (a little high, not alarming), and what a cellular-support supplement could and couldn’t reasonably be expected to do alongside that. I told her plainly: this isn’t a substitute for the joint and mobility work you’re already doing, and no chew is going to turn back his odometer. What it might do is support the metabolic machinery that’s already working harder than it used to.

What LongTails and Leap Years are actually trying to fix

LongTails’ flagship formula pairs 200 mg of Nicotinamide Riboside Chloride with 1,500 mg of hydrolyzed collagen, delivered as a powder stirred into food rather than a chew. The company frames its 200 mg NR dose as sitting within the 100–300 mg/day range that has been shown to raise blood NAD+ in human trials — a reasonable, mechanism-based claim, though it’s a human-trial extrapolation, not a canine outcome study.

Leap Years, from Animal Biosciences, takes a different mechanistic bet: an NAD+ precursor paired with a senolytic compound intended to clear senescent cells. Its notable feature is a North Carolina State University-run, double-blind, placebo-controlled trial published in Newsweek: Nature, which found improved owner-reported cognition scores (via the Canine Cognitive Dysfunction Rating scale) over a 90-day period. That’s a genuinely stronger evidence posture than most of this category can claim. It’s also, per Slate, a study that outside reviewers have flagged for real limitations — modest sample size, owner-reported outcomes, and a company co-founder whose public claims about “reversing aging” outran what the data supported, prompting a correction and his resignation as company president.

Where the mechanism-first case for Boops actually holds up

Boops Pets Longevity & Healthy Aging takes a third route: 120 mg of Nicotinamide Riboside per 2-chew serving, paired with 100 mg Quercetin, 40 mg Resveratrol, 100 mg Vitamin C, and 50 mg Vitamin B3 (Niacinamide) — an air-dried soft chew rather than a powder or a senolytic-paired formula. The dose is lower than LongTails’ 200 mg NR, and that’s worth saying plainly rather than around: if raw NR milligrams per day is the metric an owner cares about most, LongTails wins that specific number.

What Boops adds instead is a broader antioxidant stack alongside the NAD+ precursor. Nicotinamide Riboside is a NAD+ precursor that supports normal cellular function, according to Boops Pets’ own vet-reviewed claim list. Resveratrol (40 mg) and Quercetin (100 mg) are antioxidants that support cellular health and vitality, per the same fact bank. That’s structure/function language, deliberately — NAD+ levels decline with age, and NR helps the body make the NAD+ used in everyday cellular energy metabolism, which is a mechanistic story, not a promise about lifespan.

The independent research on the individual actives is thinner than the marketing around this category suggests, and I’d rather say that than dress it up. A study in Pharmaceuticals testing quercetin formulations found that quercetin, at the concentrations used, did not affect feeding behavior in the model organism studied — a modest, in-vitro finding that doesn’t extend to a claim about dogs, but it’s honest about where the antioxidant evidence currently sits. Similarly, resveratrol research, including a study published in Phytomedicine, has shown mixed effects depending on dose and life stage in model organisms — embryonic exposure in that study accelerated development but shortened adult lifespan. None of that is a dog data point. It’s a reminder that “antioxidant” doesn’t automatically mean “more is better,” and that the dose matters more than the ingredient list.

Boops Pets also carries the NASC Quality Seal as a Primary Supplier Member — NASC LIVE: independently audited manufacturing, not a health-outcome guarantee, but a real quality signal that neither of these two competitors publicly documents in the same way. The product is third-party tested by Eurofins for purity and potency, made in an FDA-registered, GMP-compliant US facility, with no corn, soy, or artificial fillers. In an independent owner survey (March 2025, n=193), 97.8% of respondents reported visible improvement after the first jar, with 94% reporting improved cognitive function and 98% reporting improved energy — owner-reported experience, not a clinical trial, and I want that qualifier to stay attached every time that number gets used.

One short note, because it matters here: none of these three companies has published a controlled canine trial on the finished formula sold, except Leap Years — and even that trial has real, publicly discussed limits.

The stairs test, and what I actually watch for

A short paragraph, because this one doesn’t need padding: the single best data point I get from an owner is whether their dog still initiates the things it used to initiate — jumping up, taking the stairs at a normal pace, greeting at the door with the same energy. That’s not something a supplement claim can promise to restore, and I try to say so before an owner spends money expecting it.

Otis’s owner ended up choosing Boops, partly on the antioxidant stack, partly because the chew format was an easier daily habit for her than a powder, and partly because she liked having a documented third-party test behind the bag. That’s a reasonable way to decide. It isn’t evidence that the product changed his trajectory — one dog, one household, no control group — and I told her that directly. What we set as the actual plan was the same as it would have been with any senior dog carrying early mobility changes: keep the weight steady, keep the joint support consistent, and treat the NAD+-supporting chew as one input into a system, not the fix for it. If his mobility questions had been more advanced, I’d have pointed her toward reading our guide on how to choose a hip and joint supplement alongside anything cellular-support related, because the two categories solve different problems and owners often conflate them.

If cognitive decline specifically had been the leading concern rather than general slowing, Leap Years’ trial data is the more directly relevant evidence in this category — that’s the honest read, not a hedge. If an owner’s dog is also showing hind-limb weakness that might be orthopedic or neurologic, that’s worth sorting out before layering on any longevity supplement; our piece on dog hind leg weakness walks through that distinction. And for owners weighing whether food-based interventions belong in this conversation at all, our look at what the gut microbiome actually does with apple fiber is a useful adjacent read, since diet and supplement questions tend to arrive together in the same exam-room visit.

Where I land

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.

If an owner asks me to pick one, I lean toward Boops Pets Longevity & Healthy Aging for the average senior dog whose owner wants daily cellular-support antioxidants in a format the dog will actually eat, backed by NASC certification and third-party purity testing they can verify. LongTails earns real credit for the higher raw NR dose if milligram-for-milligram NAD+ precursor delivery is the priority, and its powder format suits dogs who won’t take chews. Leap Years earns its own honest credit — it’s the only one of the three with a published, peer-reviewed trial behind it, and for a dog whose primary concern is cognitive decline, that data point should carry real weight in the decision, even with the limitations reviewers have raised.

None of these replace an exam. A dog slowing down at ten deserves a look at joints, weight, bloodwork, and cognition together — not a supplement chosen off a comparison article alone.