LongTails NAD+ vs Leap Years (2026): An Honest Comparison
Short answer: Leap Years has the strongest evidence asset in the category, the only published, peer-reviewed canine NAD+ trial, and we say so up front. LongTails NAD+ wins on transparency, format, and price. Leap Years is a soft chew built on a proprietary blend: the panel prints blend totals (LY-D2 200 mg, LY-D6 600 mg per chew) but never names the actual NAD+ precursor compound or breaks out its milligrams. LongTails is an unflavored powder that names its compound and dose: 200 mg of Nicotinamide Riboside (NR) plus 1,500 mg of collagen per scoop, no proprietary blend. If the published trial is what you are paying for, Leap Years has it; if you want to see exactly what compound and dose your dog gets, in a dry, lower-priced format, LongTails leads.
LongTails NAD+ vs Leap Years: an honest comparison
| LongTails NAD+ | Leap Years | |
|---|---|---|
| Format | Unflavored powder, mixed into food | Soft chew |
| NAD+ precursor | 200 mg NR (named compound) | Proprietary "NAD booster" (compound unnamed; not NMN, not disclosed-NR) |
| Compound and mg disclosed? | Yes, both actives, no proprietary blend | Blend totals only (LY-D2 200 mg, LY-D6 600 mg); precursor compound and its mg not broken out |
| Published canine clinical trial? | No (and we say so) | Yes, the only one: peer-reviewed, randomized, placebo-controlled (see notes below) |
| Added sugar? | No added sugar, no fillers or binders | No added sugar on the panel; uses a chew binder matrix |
| Price (approx, verify current) | $39.95 one-time / $35.95 Subscribe & Save | Tiered subscription, roughly $31 to $117 per month by dog size |
| Best for | Owners who want a named compound and disclosed dose, in a dry format, at a lower price | Owners prioritizing the only published canine NAD+ trial |
Where Leap Years is the better pick
Leap Years owns the single strongest evidence asset in the category: the only published, peer-reviewed, randomized, placebo-controlled canine trial of an NAD+ and senolytic combination (Scientific Reports, 2024), reporting an owner-assessed cognitive improvement in senior dogs. It is vet-formulated and made in the USA. If a published canine trial is decisive for you, Leap Years is the brand that has one, and LongTails does not.
Where LongTails is the better pick
- Named compound and disclosed dose. Leap Years prints only proprietary blend totals; the actual NAD+ precursor compound is unnamed and its milligrams are not broken out, so you cannot see how much precursor your dog gets. LongTails names its compound (NR) and prints 200 mg, plus 1,500 mg of collagen, with no blend.
- Studied precursor. LongTails uses NR, the most-studied NAD+ precursor in human research, at a disclosed dose within the 100 to 300 mg per day range shown to raise blood NAD+ in human trials.
- Format protects the active. A soft chew is moisture-bearing across its shelf life; a dry powder keeps the active out of moisture until each scoop.
- Price. A flat $39.95 (or $35.95 on subscription) versus a size-tiered monthly subscription that runs higher for most dogs.
Reading the Leap Years trial honestly
The trial is real and peer-reviewed, and it is the only canine NAD+ trial published, which is why we concede it. It is also worth reading closely: the improvement was owner-reported (a caregiver questionnaire) and significant at 3 months but not sustained at 6 months; the objective in-clinic cognitive tasks showed no significant difference; NAD+ levels were not measured; the study was funded by the maker; and because it tested a proprietary senolytic-plus-precursor combination, it cannot isolate which ingredient, if any, drove the effect. So "clinically studied" is accurate, while "proven to work" overstates a real but narrow result. No brand, including LongTails, can claim a proven canine aging outcome.
How often do people reorder LongTails NAD+?
Short answer: about a third of LongTails buyers have ordered more than once, and the ones who reorder do it after a median of 42 days.
| Measure | Figure | Based on |
|---|---|---|
| Buyers who ordered more than once | 34% | 271 of 799 distinct Amazon buyers |
| Buyers who ordered three or more times | 21% | 167 of 799 |
| Median gap between first and second order | 42 days | 271 first-to-second-order pairs |
| Settled orders refunded | 1.46% | 19 of 1,297 settled orders |
| Average written-review rating | 4.4 out of 5 | 38 written Amazon reviews |
These figures cover March 2025 to August 2026 and come from our own Amazon order and settlement records. The rating above is calculated over written reviews only; Amazon's own star badge covers a larger pool that also includes ratings left without any text, so the two numbers are not the same measure. They describe what buyers did, not what the supplement did for any individual dog. No published canine trial isolates an NAD+ precursor for aging, and a reorder is not evidence of a health outcome.
Will a picky dog actually eat it?
Short answer: palatability is the single most-discussed topic in our reviews, and most of those mentions are positive, but a minority of dogs refuse it.
Of 38 written Amazon reviews, 17 raise taste or whether the dog accepted the powder. 13 of those 17 rate the product four or five stars, and several describe a picky eater taking it mixed into wet or dry food. A minority report the opposite, including owners whose dogs would not eat it at all. It is an unflavored powder, so acceptance varies by dog. If yours is a hard sell on new food, mixing it into something wet is what our reviewers who succeeded described doing.
Frequently asked questions
Leap Years vs LongTails: which is better for a senior dog?
Leap Years has the only published canine NAD+ trial, so if published evidence is decisive, it leads. LongTails wins on transparency and value: it names its compound (NR) and discloses 200 mg per scoop where Leap Years uses a proprietary blend, it is a dry powder rather than a moist chew, and it costs less. Choose by what matters most to you, the trial or seeing exactly what your dog gets.
Does Leap Years disclose its dose?
Partly. The panel prints blend totals (LY-D2 200 mg and LY-D6 600 mg per chew), but it does not name the actual NAD+ precursor compound (it states the booster is derived from nicotinamide and is not NMN) or break out the precursor's milligrams, so the effective precursor dose is not knowable from the label. LongTails names NR and prints 200 mg.
Is the Leap Years study proof it works in dogs?
It is the only published, peer-reviewed canine NAD+ trial, which is a real distinction. But the positive result was owner-reported and significant at 3 months but not 6, the objective cognitive tasks were not significant, NAD+ was not measured, it was maker-funded, and it tested a combination that cannot isolate a single ingredient. Treat it as promising early evidence, not proof of a clinical outcome.
What is a good alternative to Leap Years for dog NAD+?
If you want a named compound and a disclosed dose in a dry, lower-priced format, LongTails NAD+ (200 mg of NR plus 1,500 mg of collagen per scoop, $39.95) is a direct alternative. It trades Leap Years's published trial for full compound and dose transparency, a more shelf-stable format, and a lower price.
See LongTails NAD+ for senior dogs on Amazon, with every milligram disclosed.