Dog probiotic dosage calculator

Updated August 29, 2026 · Built on studied doses with PubMed receipts, not label marketing. Also works for cats.

Pick the situation and the product, and this tool works out servings against the doses used in actual trials. It will also tell you two things most dosage charts won't: your pet's weight barely matters, and some situations call for a vet, not a supplement.

How this calculator decides

It anchors on the only hard number in the canine trial record: dogs with acute idiopathic diarrhea recovered faster (3.9 versus 6.6 days) on 2×10¹⁰, that is 20 billion, CFU per day of B. animalis AHC7 [1]. For diarrhea, it divides that target by your product's CFU per serving. For every other situation, no canine trial defines a CFU target, so it tells you that straight and defaults to the product's label dose rather than inventing precision.

Why doesn't weight change the dose?

Because the trials didn't dose by weight. The AHC7 study gave every dog the same 20 billion CFU per day regardless of size, and products like FortiFlora dose one sachet daily for a chihuahua or a mastiff. Bacteria are not milligrams of a drug distributing through body mass; they are colonists competing for the same length of gut lining. Weight matters for eyeballing risk (a small dog dehydrates faster on the same diarrhea), which is how this tool uses it.

Why more CFU isn't automatically better

A serving that matches a studied dose of a studied strain beats a bigger number of an unstudied one. And check the label's honesty before its arithmetic: when researchers tested 25 commercial animal probiotics, only 4 of the 15 making specific viable-count claims actually met them [2].

Deeper reading: the full dog probiotics guide and what to do tonight for dog diarrhea.