What "third-party tested" actually means
Short answer: "Third-party tested" is not a regulated phrase, so it can mean almost anything. It should mean an independent laboratory with no commercial interest in the result tested the product and issued a report — ideally accredited to ISO/IEC 17025, with the parameters you care about inside that accreditation's scope, and a batch number that matches the jar. A certificate on the manufacturer's own letterhead is quality control, not third-party testing.
"Third-party tested" appears on a great many pet supplements. Two products can both carry it and mean very different things by it.
What should "third-party tested" mean?
At minimum, that a laboratory with no commercial interest in the result tested the product and issued a report.
The important word is independent. A manufacturer testing its own product in its own laboratory is doing quality control, which is genuinely useful — but it isn't third-party testing, and the incentives are different.
How can I tell an independent report from an in-house one?
An in-house certificate of analysis is printed on the manufacturer's letterhead. A third-party report carries the laboratory's name, a report number, and usually an accreditation mark.
There is a subtler tell, too. Real laboratory results scatter. Assay methods carry inherent variability, different actives degrade at different rates, and formulators apply different overages to each ingredient.
So when a certificate lists seventeen actives and every single one comes in between 4% and 10% above its specification — none below, none unusually high — that pattern is worth a second look. Numbers that tidy are more consistent with calculation from the input formula than with measurement.
What does laboratory accreditation mean?
A laboratory can call itself independent without being accredited. Accreditation means an external body has audited its methods, equipment and competence.
The relevant standard is ISO/IEC 17025. Depending on the country you'll see it administered by:
- CNAS — China
- UKAS — United Kingdom
- A2LA or ANAB — United States
Many of these are members of ilac-MRA, an international mutual recognition arrangement. That is what allows a report issued in one country to be accepted in another.
Why does accreditation scope matter?
Because accreditation is not blanket. A laboratory is accredited for specific tests, and the certificate comes with a schedule listing exactly which ones.
Reports often flag items that fall outside that schedule — typically with a symbol and a footnote. It's easy to miss. A report can be genuine, from an accredited laboratory, and still contain individual results that sit outside what the laboratory is accredited to perform.
If a specific parameter matters to you, it's worth confirming that parameter is inside scope, not just that the laboratory is accredited in general.
What was actually tested?
Two more things a report will tell you if you read the header.
Was the sample identified by the client? Most commercial reports carry a line saying the sample was submitted and described by the client, and that the laboratory takes no responsibility for that description. This is standard. It means the laboratory tested what it was sent — not that it selected the sample from a production line.
Is there a batch number? A report with the batch number, production date and manufacturer left blank cannot be tied to the jar in your hand. It demonstrates capability. It doesn't verify a specific batch.
What do standard test panels leave out?
A typical panel covers heavy metals, microbial safety, and proximate analysis. Three things are often missing:
- Active potency — confirming the product contains what the label claims, measured rather than calculated
- Oil oxidation — for anything containing marine oil, this is the parameter most likely to fail in the real world, and it appears on almost no panel
- Water activity — which governs microbial stability over shelf life
Oxidation is the one we'd flag hardest, because it develops in the warehouse rather than at manufacture. We go into it in fish oil freshness: why some omega chews smell.
The questions worth asking
- Is the report from an accredited laboratory, or the manufacturer's own?
- Is the accreditation ISO/IEC 17025, and are the parameters you care about inside its scope?
- Does the report carry a batch number that matches the product?
- Does every batch get tested, or was this a one-off?
- Does the panel include active potency, or only contaminants?
A brand that can answer those five has done the work. A brand that can't may still have a good product — but you're taking their word for it.
Ours is a fair thing to hold to the same standard. The actives and their amounts per serving are published on the Skin + Coat Soft Chews page, and batch certificates will go up as production batches are tested — not before.
Further reading
- Fish oil freshness: why some omega chews smell — the quality failure a standard test panel will not catch.
- How to read a pet supplement label — what the guaranteed analysis commits a brand to, and what it doesn't.
- What we put on our label, and why — which certificates we publish, and which we're still waiting on.
These statements have not been evaluated by the Food and Drug Administration. Consult your veterinarian before starting any supplement.