My friend has an elderly (female, spayed) cat who has developed a GI problem (diarrhea + scooting). They are going through all of the veterinary recommended tests and treatments, but while waiting for results the vet suggested some probiotic treats (with the mindset that its unlikely to make things worse and may make things better).

How do we determine if probiotics would be helpful for the cat's condition (are they the right strain, are they alive, etc)? How can my friend determine if his vet is selling him snake oil?


tl;dr Most probiotic product labels are inaccurate and sloppy, but the two notable exceptions (from a 2011 study) were Purina's Fortiflora and IAMS Prostora Max. However, even with adequate labels, the product may not deliver a clinically significant amount of probiotics.


A study was published in 2011 (so a few years ago, the products may have changed since then) that attempted to determine if probiotics labels are adequate and accurate. The study did not consider the affect that the probiotics would have on pet health, but concentrated on label claims.

  • Weese, JS. Martin H. Assessment of commercial probiotic bacterial contents and label accuracy. Canadian Veterinary Journal 2011;52:43–46. (full text)

First, labels were assessed for adequacy. This meant:

Product labels were scrutinized; this included an assessment of spelling of contents, if contents were clearly described (genus and species), if the number of viable organisms was stated, if there was an expiry date, and if specific health claims were made.

The results were:

If an adequate label is defined as one that contains specific (and valid) bacterial names (genus and species), with no spelling errors and a clear statement of number of viable organisms that are expected, then only 8 (32%) products were properly labeled. If a more stringent definition of an adequate label is used, which includes a requirement that the product identify the specific bacterial strain that is present, then no products were adequately labeled.

Second, the product was tested to determine the species and quantity of probiotics present in the product. The result was:

Only 4/15 (27%) products that had specific claims of viable organisms met or exceeded their label claim. ... It is unclear whether the products with low levels actually had the stated numbers at the time of manufacturing or whether the stated levels were never present. Regardless of whether or not the organisms died during storage or were never there is irrelevant for the patients.

However, meeting the label claim does not ensure that the product delivers a clinically significant amount of probiotics.

For example, 1 product contained 3194% of claimed Bacillus subtilis and mixed lactic acid bacteria, yet the label claim was very low... Even though this product exceeded the label claim, the number of viable organisms provided per recommended dose (1/4 to 3 tsp) would be quite low and unlikely to be effective.


Colonization and clinical studies involving dogs and cats, which tended to use empirical dosing, have used doses of 200 million to 500 billion CFU/d, levels that are unachievable with most of the tested products.

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