The Problem with Proprietary Blends in Pet Supplements
By Michael Koch, Founder · 92 Days LLC ·
Look closely at almost any joint chew on the shelf and you'll eventually find a line that says something like "Joint Support Complex" followed by one number in milligrams — with several ingredient names listed underneath it, and no individual amounts next to any of them. That's a proprietary blend. It's completely legal. And it's the single biggest reason two supplements can list the exact same ingredients and do completely different things for your dog.
What the Law Actually Allows
Under federal regulation 21 CFR 101.36, a brand is allowed to group several ingredients under a blend name — "Proprietary Blend," "Joint Complex," "Mobility Matrix," whatever they want to call it — and disclose only the combined weight of everything in that group. The individual amount of each ingredient inside the blend doesn't have to appear anywhere on the label.
This isn't a loophole brands are exploiting against the rules. It's written directly into the rule. The Dietary Supplement Health and Education Act of 1994 carved out this exception specifically so companies could protect a formula's exact ratios as a trade secret. The intent was reasonable — protecting genuine intellectual property. The effect, decades later, is a labeling format that makes it functionally impossible for a pet parent to know what they're actually buying.
The One Rule That Actually Helps You
There's exactly one piece of useful information the law does require inside a proprietary blend: the ingredients have to be listed in descending order by weight. Whatever's listed first is present in the largest amount. Whatever's listed last is present in the smallest amount — and "smallest amount" can legally mean a single milligram in a multi-gram blend.
How to use this: If a "Joint Support Complex" lists glucosamine first and five other ingredients after it, glucosamine is probably present in a real amount — and everything listed after the third or fourth ingredient may be in the formula at a dose too small to do anything at all. The order is the only clue you get, and most pet parents don't know it's there to read.
Why This Specific Format Is Common in Joint Chews
Joint supplements are a near-perfect fit for this labeling exception, and that's exactly the problem. A brand using a blend can list familiar names like glucosamine, chondroitin, or MSM — the words a dog owner is actually scanning the label for — and satisfy the legal requirement to disclose them, while never revealing that several of those ingredients are present at a fraction of a clinically meaningful dose. The blend format lets a brand name what's expected without committing to how much of it is actually in there.
This is the opposite of how we built our own label. Every one of our 9 actives — including the ones listed above — has its own disclosed milligram amount, with nothing grouped under a blend name to hide behind. The names being common doesn't make the formula generic; what makes a formula generic is refusing to say how much of each one is actually inside.
The label still looks complete. It still names every ingredient a knowledgeable buyer is scanning for. That's exactly the point — the blend format lets a brand check every box a label-reader is looking for without committing to a real number for any of them.
Why a Brand Would Choose This on Purpose
Sometimes it really is about protecting a unique ratio. More often, in this category, it's about cost. Boswellia extract and hyaluronic acid cost meaningfully more per milligram than fillers or cheap glucosamine sources. A blend format lets a brand list an expensive ingredient by name — which is what shows up in marketing copy and product comparisons — while only including a token amount of it in the actual jar.
There's no way to catch this from the label alone. The Supplement Facts panel is fully compliant. Nothing about it is false. It's just structured so the one number you'd actually need — how much of each individual ingredient is in there — is the one number the format doesn't require.
What a Fully Disclosed Label Looks Like Instead
A brand that isn't using this exception has a Supplement Facts panel structured completely differently — and once you've seen the difference, it's easy to spot:
✓ Every ingredient has its own line — Glucosamine HCl ... 1000mg. Chondroitin Sulfate ... 300mg. Each one stated separately, not nested under a blend heading.
✓ No "Complex," "Matrix," or "Blend" heading — If you don't see one of those words anywhere on the panel, there's no blend to hide amounts inside.
✓ The math is checkable — Add up the individual amounts and they should roughly match any "total actives" figure the brand advertises elsewhere.
Why Legacy Furmula™ Doesn't Use One
There's no "Hip & Joint Complex" anywhere on our label. Every one of our 9 active ingredients — glucosamine, MSM, chondroitin, turmeric, boswellia, hyaluronic acid, hemp seed oil, vitamin C, and black pepper extract — has its own line and its own milligram amount. You don't have to know about descending-order rules or trade-secret exceptions to understand exactly what's in the jar, because we never built the label in a format that requires that knowledge in the first place.
That's not a regulatory requirement we're following. It's a format we chose not to use, even though the law would have let us.
Written by Michael Koch · Founder, 92 Days LLC
These statements have not been evaluated by the FDA. For educational purposes only. Not legal advice — consult the FDA's own guidance or an attorney for compliance matters.