Did Your Dog's Energy Drop After Turning 8? What NAD+ Precursor Chews Can and Can't Do

By Tamara Shearer, DVM, MSTCVM, CCRP, CVPP, CVA, CHPV, CTPEP

✓ Medically reviewed by Tamara Shearer, DVM, MSTCVM, CCRP, CVPP, CVA, CHPV, CTPEP — July 13, 2026

Longevity & NAD+ · July 21, 2026 · 5 min read

If your dog's energy dropped after turning 8, here's what NAD+ precursor chews can and can't do.

First, Rule Out the Fixable Before You Reach for a Chew

Book the physical exam before you buy the supplement. A dog whose energy dropped in the months after his eighth birthday is telling you something, and “he’s just getting old” is the one explanation that quietly hides the treatable ones. Ask your veterinarian for a senior workup: a thyroid panel, bloodwork for anemia and for kidney or liver disease, a careful check for the low-grade arthritis pain that steals a dog’s willingness to move, and a heart evaluation if there is any cough or exercise intolerance. Hypothyroidism, osteoarthritis, and early cardiac disease all read as “low energy” from the couch, and each one has real management. A NAD+ precursor chew cannot fix a sluggish thyroid gland or an aching hip. Clearing those possibilities first keeps your dog’s comfort — his quality of life — at the center, which is where a decision like this belongs.

What Is a NAD+ Precursor, and Why Would Age 8 Change Anything?

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme that every cell relies on to turn food into usable energy inside its mitochondria. Levels of it tend to fall with age, and not only because cells make less — aging tissue also destroys more of it. One well-described culprit is an enzyme called CD38, an NADase whose activity climbs as an animal gets older. A “precursor” is simply a raw building block the body converts into NAD+; the two studied most are nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). The premise behind a chew is to hand the cell more of that raw material so NAD+ does not slide as far. Around ages 7 to 9, many dogs cross into their senior years — large breeds sooner, small breeds later — as metabolism slows and muscle upkeep gets less efficient. That timing is why the eighth birthday is so often when owners start asking about it.

What Does the Human Evidence Actually Show?

The picture is genuinely encouraging on one narrow point and thin on the rest. In a randomized, placebo-controlled trial of 140 adults, eight weeks of NR raised whole-blood NAD+ in a clean, dose-dependent way — roughly 22% at 100 mg, 51% at 300 mg, and 142% at 1,000 mg — with no serious adverse events and none of the flushing associated with older niacin forms. A separate controlled trial in middle-aged and older adults reached the same safety conclusion: chronic NR is well tolerated and reliably lifts NAD+. So the claim that a precursor “raises NAD+” is real and defensible. The honest caveat is what comes next. A 2025 review of NAD+ precursor trials in human ageing found that those measurable NAD+ increases have not yet translated into consistent gains in strength, stamina, or everyday vitality. Raising the number is not the same as changing how a body feels — a distinction worth holding onto before you extrapolate to your dog.

What Do We Actually Know in Dogs?

Less than the marketing implies, and the one dog trial worth knowing is instructive. A blinded, placebo-controlled study enrolled 70 dogs aged 10 and older and tested a chew that pairs an NAD+ precursor with a senolytic, a compound meant to clear worn-out “senescent” cells. At the three-month primary endpoint the treated dogs improved on an owner-scored cognition scale, the Canine Cognitive Dysfunction Rating (CCDR) — a real if modest signal for the aging brain. But activity measured by wearable monitors, along with gait speed and frailty scoring, showed no statistically significant change, and the work remains a preprint that has not cleared peer review. Read that carefully: the measured benefit was cognitive, not the exact “more pep in the yard” outcome most owners are hoping to buy. Across the broader veterinary literature, canine anti-aging science is still early. The best-supported longevity lever in dogs is not a supplement at all but lifelong lean body weight — a landmark study found that a 25% dietary restriction extended lifespan and delayed the onset of age-related disease.

How Do You Read the Label Without Wasting Money?

Do these four things standing at the shelf.

• Find the NASC Quality Seal. The National Animal Supplement Council seal means the maker passed an independent audit and submits to random label-accuracy testing — your baseline that what is printed on the panel is actually in the chew.
• Confirm the precursor is named with a dose. Look for “nicotinamide riboside” or “NMN” and a real milligram amount per chew, not a vague “cellular support blend.”
• Ask for a certificate of analysis. A current third-party COA tells you the batch was tested for identity and purity.
• Match your expectation to the evidence. These are structure/function products that may help support normal cellular energy metabolism; none is cleared to treat, cure, or reverse disease, and a label promising “age reversal” is a reason to set it back down.

What about the resveratrol and quercetin on the label?

Many longevity chews pair a precursor with antioxidants such as resveratrol and quercetin. Both are legitimate research subjects — quercetin is studied as a senolytic, resveratrol as a cellular-health antioxidant — but the canine evidence is largely preclinical, and oral resveratrol absorbs poorly unless it is specifically formulated for uptake. Treat those additions as reasonable companions to the precursor, not as proof the product works.

Where That Leaves You and Your Dog

Your practical next step is the vet visit, then a clear-eyed trial. If the workup comes back clean and you and your veterinarian decide to try an NAD+ precursor chew, choose an NASC-listed product with a named, dosed precursor, commit to a defined 8-to-12-week window, and judge it against something you can actually observe — willingness to rise, interest in the walk, ease on the stairs. Keep the food portioned and the body lean the whole time, because that is the lever with the strongest evidence behind it. And keep returning to the only question that truly matters at this stage of life: is he comfortable, and is he enjoying his days. Whatever the chew does or does not do, that answer stays at the center.