What Does Third-Party Testing Say About Potency?

Dennis keeps the jar for Tofu, his 8-year-old neutered male Pomsky in Flint, Michigan, next to the kibble bin, and after three weeks the loose evening stools are still coming and going. He wonders whether the 20 billion CFUs promised on the front are still in the chew at all.

What should that number actually guarantee by the time a dog eats it? My answer is direct: trust only potency verified through expiry by an independent lab, with strain names, CFU per strain, and method listed. Anything less is a manufacturing snapshot, not a feeding dose.

What a CFU count means after the jar leaves the plant

Live bacteria die on a curve. Heat during extrusion, moisture in a soft chew, oxygen in a half-closed pouch, and time on a warehouse shelf all reduce viable colony-forming units. A count taken on the day of blending tells you what went into the mixer, not what reaches the bowl two months later.

That is why I prioritize expiry CFU over manufacture CFU. A responsible label states viable count through the best-by date when stored as directed, ideally per strain — for example, Enterococcus faecium plus Lactobacillus acidophilus with a separate CFU for each — rather than one blended total. A balanced gut microbiome supports overall immune function, but only live, identified organisms in sufficient numbers may help support normal digestion alongside food-first care like steady fiber and hydration.

Expectations matter here. Even a well-verified product may help support stool consistency over 2–4 weeks rather than firming the next stool overnight.

Independent verification versus in-house assays

Any manufacturer can run its own plate count. Third-party testing means a separate accredited laboratory repeats the work without a stake in the result.

What I look for is separation and specificity. The National Animal Supplement Council explains its third-party quality system and seal program for companion-animal supplements, including independent audits and testing expectations. That kind of outside oversight does not prove efficacy, but it raises the bar above self-reported numbers.

The NIH Office of Dietary Supplements notes in its probiotics review that potency, strain identity, and viability through storage vary widely and that labels often do not reflect live content at use. The physiology is straightforward: stomach acid and bile reduce survivors, so the starting viable dose and protective format determine how many organisms reach the colon alive.

In practice, I reject combined proprietary-blend totals with no strain breakdown, no expiry guarantee, and no named lab or method.

Reading a certificate of analysis without a lab coat

Ask the company for a lot-specific Certificate of Analysis from the outside lab. It should tie to your lot number, not just a one-time example from last year.

Check four lines. Strain identity confirmed by a DNA-based method. Viable CFU per strain at or near expiry, not only at release. Contaminant screens for aerobic plate count, yeast and mold, Salmonella, and E. coli. And method references, such as plate count or flow cytometry, with storage conditions.

Marilyn in Pomona, California, did this for Bianca, her 3-year-old spayed Bull Terrier mix, after a chicken-based chew softened in a warm pantry. One email produced a lot-matched sheet showing per-strain expiry counts; the other brand sent only a marketing spec sheet. She kept the first jar and moved the bin away from the stove, and the choice took one afternoon.

That is the lifecycle to remember: manufactured, stored, then fed. For context on companion issues that often get blamed on probiotics alone, I point owners to the same workup I use for gas before reaching for a supplement and to when enzymes are medicine versus marketing. Fiber form matters too — pumpkin fiber is a gentle, natural source of both soluble and insoluble fiber — and constipation rumors deserve the same label scrutiny.

What would change my position is lot-level, third-party data showing stable expiry CFU linked to a defined digestive outcome in dogs. Until then, I stay with food-first foundations, needle-based support where appropriate, and only probiotics that prove survival in the jar.