First, understand the regulatory gap
Pet supplements are not approved by the FDA the way medicines are. They occupy a space between food and drug that is regulated unevenly — some oversight of manufacturing and labelling, very little pre-market review of whether a product does what it implies.
This is not a scandal, but it does shift the burden. Nobody has checked the bottle before it reached the shelf. The company's own standards are, in practice, the standard — which makes the company's willingness to show its work the most informative signal available to you.
1. The amounts are disclosed
The single most useful thing on a label is a number beside each active ingredient. Without it you cannot compare the product to the research, to a competitor, or to what your vet recommends.
"Proprietary blend" is where amounts go to hide. A blend line tells you the total weight of everything in it, which lets a company put a meaningful amount of the cheap ingredient and a token amount of the expensive one behind a single number. There are legitimate reasons to protect a formula, but they conflict directly with your ability to evaluate it.
2. The ingredient is identified specifically
"Mushroom extract" is not an ingredient. Which mushroom, which part — fruiting body or mycelium — and extracted how? "Collagen" does not say the source or whether it is hydrolysed. "Peptides" says almost nothing at all.
Specificity is cheap for an honest formulator and expensive for a vague one. Its absence is informative.
3. The dose matches the research
An ingredient present at a tenth of the studied amount is there so it can appear on the label. The industry term is fairy dusting, and it is common precisely because most buyers check whether an ingredient is present, not how much.
Checking requires two things: the amount disclosed on the label, and knowing what amount was actually studied. Our piece on how ingredients are studied covers finding the second.
4. It is made somewhere with real standards
Ask where the product is manufactured and to what standard. cGMP — current Good Manufacturing Practice — covers cleanliness, process control, record keeping and batch traceability. Facilities differ enormously, from pharmaceutical-grade compounding environments to contract packers running whatever the client ordered.
Contract manufacturing is normal and not a mark against a brand. Not knowing who makes your product, or declining to say, is.
5. Every batch is third-party tested
This is the one that catches most problems. Independent laboratory testing on the finished product should cover three things:
- Identity — the ingredient is what the label says it is.
- Potency — it is present at the stated amount, within a defined tolerance.
- Purity — heavy metals, microbial contamination and, for botanicals, mycotoxins are below defined limits.
Note finished product. Testing the raw ingredient on arrival is necessary but not sufficient; potency can be lost in processing and over shelf life.
6. The results are published by lot
Testing that you cannot see is a claim, not evidence. The meaningful version is a certificate of analysis published per lot, matched to the lot number printed on the box in your hand.
A single COA on a website, undated, for an unnamed batch, is a marketing asset. A searchable library where any lot — including expired ones — stays available is a different level of commitment. We explain how to read one in this guide, and our own library lives at the certificate library.
7. The formula is species-specific
A cat is not a small dog. Cats have different essential nutrients, different clearance rates and different sensitivities — taurine being the clearest example of something a cat must get from diet.
A product marketed "for dogs and cats" in a single formulation is either broad enough to be conservative for both, or built for one and portioned for the other. It is worth asking which.
8. The claims are careful
Read the verbs. Supports, helps maintain and contributes to are structure-function language and appropriate for a supplement. Treats, cures, prevents and reverses are drug claims, and a supplement making them is telling you something about the company.
Restraint in marketing correlates with restraint in formulation more often than you would expect.
9. There is a real way to get it wrong and get your money back
Two practical signals. First, a genuine guarantee — one that survives an opened, half-used box, since that is the only state in which you could possibly have evaluated the product. Second, a way to check suitability before you buy: a screener against your animal's medications and conditions, or access to a veterinarian who can tell you it is not a fit.
A company that makes it easy to conclude "not for my pet" is one that expects to be judged on outcomes.
- How much of each active is in one serving?
- Who manufactures it, and to what standard?
- Which independent lab tests it, and for what?
- Can I see the certificate of analysis for the lot I am buying?
- What happens if it does not work for my animal?
Frequently asked
Not reliably. Price reflects ingredient cost, testing, manufacturing standard and marketing spend in unknown proportions, and marketing is frequently the largest. Cheap products, though, are constrained by arithmetic: genuine ingredient amounts and per-lot third-party testing both cost real money, and a very low price means something was left out.
The National Animal Supplement Council is an industry body whose members submit to facility audits, adverse-event reporting and labelling standards. It is voluntary self-regulation rather than government oversight, so it is a meaningful positive signal rather than a guarantee.
Yes — particularly if your animal takes any medication, has a diagnosed condition, is pregnant, or is very young or very old. Supplements can interact with medications, and your vet knows your animal's history. Bring the full ingredient list with amounts, which is another reason those numbers need to be on the label.
Thirty days is a reasonable minimum for anything working through tissue turnover. Note where you started — a written note and a photo — because month-old memory is unreliable, and change one variable at a time so you can attribute what you see.
Not sure it is right for your pet?
Our eligibility screener checks your animal's medications and conditions against every ingredient on the formulation sheet. One minute, eight questions, and it will tell you if we are not a fit.