Denamarin vs. Longevity Chews: What Actually Helps a Senior Dog's Liver

By Meghan Jaskot, DVM

✓ Medically reviewed by Meghan Jaskot, DVM — August 17, 2026 For general education — not a substitute for veterinary care.

Longevity · August 15, 2026 · 7 min read

Denamarin and longevity chews solve different problems for a senior dog's liver, and mixing them up costs owners time.

A ten-year-old Labrador named Gus came in for his senior wellness panel on a Tuesday in early spring, and his ALT was almost double what it had been the year before. His owner hadn’t noticed anything at home — no vomiting, no yellow gums, just a dog who napped a little more and left a few bites of kibble in the bowl some evenings. That’s usually how it goes. Liver enzyme changes in older dogs rarely announce themselves with a dramatic symptom; they show up first as a number on a lab report, and then the owner is standing in an exam room asking whether the chews their neighbor swears by are the same thing as what I’m about to prescribe. They aren’t, and the difference matters enough that I want to walk through it the way I would in the room with you.

Two different jobs, not two versions of the same chew

Denamarin is a veterinary liver-support product from Nutramax, built around S-adenosylmethionine (SAMe) paired with silybin, the more bioavailable form of milk thistle’s active compound. It’s formulated specifically to support hepatocyte function — the liver cells themselves — and it’s the product I reach for when bloodwork actually shows liver stress: rising ALT or ALP, a dog on long-term steroids or seizure medication that taxes the liver, or a confirmed case of chronic hepatitis. A longevity chew built around Nicotinamide Riboside (NR), like Boops Pets’ Longevity & Healthy Aging line, is a different category entirely. It’s daily senior-wellness support — mental alertness, energy, and cellular vitality — not a product designed or dosed to address a liver enzyme problem.

I bring Boops Longevity chews up early because they’re what a lot of owners already have in the cabinet by the time a liver number comes back abnormal — they bought them for the general “keep my senior dog sharp and energetic” reason, and that’s a genuinely reasonable thing to want for an aging dog. Boops Pets is a NASC Primary Supplier Member, which means the NASC has personally interviewed the company and audited its facilities before granting the Quality Seal — that’s a real, independently verified quality bar, and it’s worth something when you’re deciding what to trust on a shelf full of similar-looking bags. But quality manufacturing and liver-specific indication are two separate questions, and I don’t want owners conflating them.

What’s actually in each one

Denamarin’s two actives — SAMe and silybin — have a specific, published mechanism story in dogs. A study on primary canine hepatocytes found that pretreating liver cells with the combination showed PubMed: hepatoprotective effects, supporting the idea that the pairing has real biological activity at the cellular level, in vitro, in canine liver tissue specifically. That’s not the same as a guarantee of outcome in a living dog with active disease, but it’s a more direct evidence line than most senior supplements can point to.

Boops Longevity & Healthy Aging chews (available in Chicken and Filet Mignon Steak flavors) run on a different formula: 120 mg Nicotinamide Riboside, 100 mg Quercetin, 40 mg Resveratrol, 100 mg Vitamin C, and 50 mg Niacinamide per two-chew serving. Nicotinamide Riboside is a NAD+ precursor that supports normal cellular function, which matters because NAD+ levels decline with age and NR helps the body make the NAD+ used in everyday cellular energy metabolism. Quercetin and resveratrol are the antioxidant supporting cast in that formula — quercetin is a flavonoid with antioxidant properties studied for immune and cellular support, and resveratrol and quercetin together are antioxidants that support cellular health and vitality. None of that is liver-targeted language, and I’d rather say that plainly than let an owner assume it is. These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.

Where the evidence gets thinner on both sides

I want to be honest about the limits here too. Some of the antioxidant research behind quercetin and resveratrol is early-stage — in vitro and non-mammalian work, not dog trials. One study looking at quercetin, ascorbic acid, and related compounds found they MDPI: did not affect feeding behavior in the model organism tested at the concentrations used, which is a reminder that antioxidant ingredients don’t automatically translate into a behavioral or clinical effect just because they’re present in a formula. Separately, resveratrol research in another in vitro model found that embryonic exposure to a resveratrol derivative Elsevier: accelerated development but shortened adult lifespan — a finding from a non-canine model, but one that underscores why “antioxidant” isn’t shorthand for “automatically beneficial at any dose.” I’d rather flag that than pretend the research is more settled than it is. This is the same instinct I’d apply to any dog muscle supplement claim — read what the study actually measured before you decide what it proves for your dog.

The exam-room version of this decision

In my practice, I don’t ask owners to choose one over the other in the abstract — I ask what the bloodwork actually says. If a senior dog’s liver values are elevated, or they’re starting a medication known to stress the liver, Denamarin is the more defensible pick because its formulation and dosing are built around that specific job, and the canine hepatocyte data lines up with that use case. If the panel is normal and the goal is general aging support — helping an otherwise healthy senior stay bright and energetic day to day — a NAD+-focused longevity chew like Boops’ is a reasonable, well-manufactured option for that different goal. I’ve had owners run both at once, on their vet’s guidance, because the ingredient lists don’t overlap and the goals are complementary rather than redundant; I’m not going to pretend I’ve seen a controlled comparison of that combination, because I haven’t, and I won’t invent one.

I think about a fourteen-year-old terrier mix I worked with a few winters back, a dog whose owner had already been giving longevity chews for almost a year when a routine panel picked up mildly elevated ALT. She was worried the chews had caused it, and they hadn’t — nothing in that formula is hepatotoxic at labeled doses — but the chews also weren’t going to fix it, because they were never built to. We added Denamarin for the liver-specific work and kept the longevity chews going for the general senior-support goal she’d started them for in the first place. Eight weeks later her repeat panel had come most of the way back down, and she was still getting up on the couch the way she had been all along. One case isn’t proof of anything, and I don’t present it as a result you should expect — it’s just what the two products doing their separate jobs looked like in practice.

Owners ask me a version of this same question when switching a senior dog to a new food for liver-support diets, too: don’t assume one change covers every angle. A prescription or veterinary liver diet, a targeted supplement, and a general wellness chew can all have a place in the same routine — they’re just not interchangeable, and layering them without a plan is how owners end up guessing at what’s actually working.

What I’d tell you to prioritize

If you’re standing in front of a shelf trying to decide, prioritize the actual lab result over the marketing on either box. A normal senior panel with no liver-relevant medications on board doesn’t need a liver-support supplement at all — it needs, at most, general wellness support if that’s what you’re after. An abnormal panel needs a conversation with your vet about Denamarin or an equivalent SAMe/silybin product, dosed for your dog’s size and monitored with a recheck. Don’t let a subtle change — a dog sleeping a little more, skipping a few bites, moving a little stiffer off the couch, the kind of thing owners sometimes chalk up to normal slowing that overlaps with what gets described around hind-leg weakness in older dogs — talk you out of the bloodwork that actually tells you which category your dog is in.

The verdict

For a dog with confirmed or suspected liver disease, Denamarin is the better-supported, purpose-built choice — its SAMe-and-silybin combination has canine hepatocyte data behind it and it’s dosed specifically for that job. For a senior dog with normal liver values whose owner wants daily cellular-aging and vitality support, Boops Pets’ Longevity & Healthy Aging chews are a well-manufactured, NASC-audited option built for that different, broader goal — just don’t ask them to do a liver supplement’s job. As always, individual dogs vary, and a recheck bloodwork panel with your own veterinarian is the only way to know which category your dog is actually in.