How to Read a Certificate of Analysis for a Pet Supplement
What's on one, what should be, and the single distinction that decides whether it means anything.
"Third-party tested" appears on an enormous number of supplement bottles, and by itself it's a phrase, not evidence. The document behind that phrase is a certificate of analysis, usually shortened to COA, and asking for one is the fastest way to find out how seriously a company takes its own claims.
A certificate of analysis is a laboratory report for one specific batch of product. A useful one names the lot number, the testing laboratory, the analytical method used, the specification for each test, and the measured result alongside it. If it doesn't tie to a lot number you can match to your bottle, it tells you very little about what you bought.
Most pet parents never ask for one, which I understand, because the documents look intimidating and nobody explains what the columns mean. They're a lot more readable than they appear, and you don't need a chemistry background to get real information out of one!
There's also one distinction inside these documents that decides whether the whole thing is worth reading, and it catches people who are otherwise doing everything right. I'll get to it below.
What a COA Is, and What It Isn't
A COA is a test report. A laboratory received a sample, ran specific assays on it, and recorded what came back. It's a snapshot of one batch on one date, and that's the whole of what it claims to be.
It isn't a certification, despite the name. Nobody is accrediting the product. It isn't an endorsement of the formula, and it says nothing at all about whether the dose is useful or the ingredient form absorbs well. A product can have an immaculate COA and still be underdosed to the point of uselessness, which is why testing sits at number four in my process rather than number one.
There's also a related document worth knowing about, because it gets substituted for a COA more often than it should. A certificate of conformance, or COC, is a supplier's written statement that a material meets an agreed specification. It's an assertion. A COA carries the data behind the assertion. If you ask for testing and receive a one-page document with no numbers on it, check the title.
The Anatomy of the Document
Once you know what you're looking at, a COA breaks down into four parts.
The header identifies the sample. Product name, lot or batch number, date of manufacture, date the sample was received, and date of testing. The gap between manufacture and testing is worth a glance, since a sample tested eight months after it was made is telling you about a different product than the one that left the line.
The laboratory tells you who ran the work and whether they're independent of the company selling you the product. The detail I look for here is ISO/IEC 17025 accreditation, which is the international standard for testing and calibration laboratories. An accredited lab has demonstrated competence in the specific methods it's accredited for, and that's a meaningfully different thing from a lab that simply owns equipment. In-house testing isn't automatically a problem, and plenty of good companies run their own quality control alongside outside verification. I'd just want to see both.
The method column names the analytical technique used for each test. You'll see things like HPLC or UPLC for potency assays, ICP-MS for heavy metals, and HPTLC for botanical identity. You don't need to know how these work. What matters is that a method is named at all, because a result with no method behind it can't be evaluated or repeated.
Specification versus result is the pair of columns that carries the actual information. The specification is the acceptance limit the company set, and the result is what the lab measured. Both need to be present. A document that reports only "conforms" or "meets specification" without the numbers is asking you to take the company's word for where the bar was set, which defeats the purpose of asking.
Raw Material or Finished Product?
This is the distinction I mentioned, and it's the one that most often makes an otherwise impressive COA meaningless.
When a company buys an ingredient, the supplier sends a COA for that raw material. The turmeric extract arrived, it was tested, it assayed at the stated curcuminoid percentage, the heavy metals came back within limits. All true, all useful to the manufacturer, and all describing a barrel of powder rather than the bottle in your hand.
A finished-product COA tests the thing you're actually giving your dog, after blending, encapsulation, and whatever else happened between the barrel and the bottle. That's where you find out whether the blend was homogeneous, whether the claimed amount per serving is really there, and whether anything was introduced during manufacturing.
Raw material testing is necessary and I'm glad when companies do it. It just can't stand in for the finished product, and a fair number of brands present it as though it can. So when you receive a COA, look at the product name in the header. If it says "Organic Boswellia Serrata Extract 65%" and the product you bought is a six-ingredient joint chew, you've been handed the ingredient's paperwork.
The other half of this is the lot match. The certificate should reference a lot number, and that lot number should appear on your bottle or correspond to a batch currently shipping. A COA for a lot produced three years ago tells you a company tested something once.
What Should Actually Be Tested
Not every product needs every panel, and which tests matter depends on what the ingredient is and where it came from.
Identity
Identity testing confirms the material is the species it claims to be. This matters most with botanicals, where substitution and misidentification are documented problems, sometimes through carelessness in the supply chain and sometimes deliberately. HPTLC produces a chemical fingerprint that can be compared against a reference for that plant. DNA barcoding also comes up, and there's a real limitation worth knowing: extraction with heat and solvents degrades DNA, so barcoding works well on raw plant material and much less well on finished extracts. A company that uses the appropriate method for the material has thought about this.
Potency
Potency, sometimes labeled assay, measures how much of the active compound is present against what the label claims. For a standardized extract this is the number that justifies the price, since a 95% curcuminoid extract and a 20% one are very different materials wearing similar names.
Heavy Metals
The standard panel covers lead, arsenic, cadmium, and mercury, usually by ICP-MS. This matters most for ingredients that concentrate what's in their environment: roots and rhizomes, leafy botanicals, kelp and other sea vegetables, and marine oils.
Now, some nuance here, because this topic gets used to frighten people. Trace heavy metals are present in soil, water, and therefore in plants and animals, including in food. Detecting a measurable amount in a botanical supplement is expected. The question is never presence, it's whether the amount sits within a sensible limit for the serving size, which is exactly what the specification column exists to tell you. California's Prop 65 warnings often come up in this conversation too, and those thresholds are set as disclosure triggers well below levels associated with harm, so a warning label is a signal to look at the numbers rather than a finding that a product is unsafe.
Microbials
A microbial panel typically includes total aerobic plate count, yeast and mold, and specific pathogens such as Salmonella and E. coli. This becomes more important with dried botanicals, powders, and anything containing animal-derived material.
Oxidation, for Oils
Fish oil and other marine oils get their own set of measurements, and these are the ones I most wish more companies published! Peroxide value measures primary oxidation products. Anisidine value measures secondary ones, the breakdown compounds that form as oxidation progresses. TOTOX combines the two into a single figure, calculated as twice the peroxide value plus the anisidine value.
The voluntary industry monograph most often referenced sets limits of 5 for peroxide value, 20 for anisidine, and 26 for TOTOX. An oil tested well under those numbers is fresh. A company that measures this and shows you is a company that knows oxidation is the main thing standing between a good omega-3 product and a bad one.
What a Good One Looks Like
Run down this list when a COA lands in your inbox:
- It's for the finished product, not a raw material, and the product name matches what you bought.
- There's a lot number, and it corresponds to a batch currently being sold.
- The lab is named, is independent of the brand, and ideally holds ISO/IEC 17025 accreditation.
- Each test names its method, so the result could be repeated by someone else.
- Specifications and measured results both appear as numbers, not as the word "conforms."
- The panels fit the ingredient. Botanicals get identity testing, marine oils get oxidation values, soil-grown material gets heavy metals.
- The dates are recent and the gap between manufacture and testing is short.
How to Ask for One
Email the company and be specific, because a vague request gets a vague answer. What I ask for is the finished-product certificate of analysis for the lot number printed on my bottle.
The response itself tells you something regardless of what arrives. Companies with good testing programs send the document, sometimes within hours, because it's already sitting in a folder. Companies without one take a while and then explain their commitment to quality in three paragraphs.
A reasonable middle case exists too. Some smaller brands test on a schedule rather than every lot, and they'll tell you that plainly and send you the most recent one. I'd rather have that honest answer than a polished non-response, and it's information I can work with.
Third-party testing is the fourth of seven checks I run before a supplement goes on my shelves. The full framework is here: How I Vet a Dog Supplement Before It Goes on My Shelf.
Related reading: What a proprietary blend actually hides · How to tell if a fish oil has gone rancid
Common Questions
What Is a Certificate of Analysis?
A certificate of analysis is a laboratory report for one specific batch of a product. It lists the tests that were run, the method used for each, the acceptance specification, and the measured result. It documents what was found in that batch on that date, and it makes no claim about whether the formula is well dosed or the ingredient forms absorb well.
What's the Difference Between a COA and a Certificate of Conformance?
A certificate of analysis carries measured data from laboratory testing. A certificate of conformance, or COC, is a written statement that a material meets an agreed specification, with no test results attached. Both have a place in a supply chain, and only one of them lets you see numbers. If you asked for testing and received a document with no results on it, check which one you were sent.
Why Does the Lot Number on a COA Matter?
Testing applies to the batch that was tested and nothing else. A lot number lets you confirm the certificate describes the product in your hand rather than something made three years ago. Batch-level testing means a company is checking what ships continuously, which is a different standard of quality control from testing a product once and referencing that document indefinitely.
Is a Raw Material COA Good Enough?
It's useful, and it can't substitute for finished-product testing. A raw material certificate describes an ingredient before it was blended, encapsulated, or bottled, so it can't confirm the amount per serving in the final product, whether the blend is homogeneous, or whether anything was introduced during manufacturing. Check the product name in the certificate header against what you actually bought.
Should I Worry If a COA Shows Detectable Heavy Metals?
Detection alone isn't the issue. Trace heavy metals occur naturally in soil and water and therefore appear in plants, animals, and ordinary food, so measurable amounts in a botanical supplement are expected. What matters is whether the result falls within a sensible specification for the serving size, which is why the specification column sits next to the result column. Certificates that report results with no specification beside them are harder to interpret for exactly this reason.
What Is TOTOX on a Fish Oil COA?
TOTOX is a combined measure of oxidation in an oil, calculated as twice the peroxide value plus the anisidine value. Peroxide value reflects primary oxidation products and anisidine value reflects secondary ones, so the combined figure captures both early and later stages. The voluntary industry monograph commonly referenced sets limits of 5 for peroxide value, 20 for anisidine, and 26 for TOTOX. Results well below those figures indicate a fresh oil.
About the author
Kayleigh is the founder of The Organic Dog Shop. She holds NTP and FDN-P credentials and has completed coursework through the College of Integrative Veterinary Therapies in natural animal nutrition and naturopathic animal health care. She reads every supplement panel in the shop before it ever gets listed.
Here's to healthier, happier dogs!
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.