What Is In Your Dog’s Kefir?

Ideally, I would be able to make the study available for you to download so that you can read the study yourself, but unfortunately, this study is not open access at this point.

Do you feed Kefir to your dogs or cats?

In a recent study conducted at the University of Illinois. Researchers analyzed the label and website claims against the actual products. Six different companies’ products were tested. Brand B, C, D, and F were shipped frozen and were kept frozen until 24 h before analysis. These products were thawed, then refrigerated at 4 °C before analysis as per individual manufacturer instructions. Product E and the Yogurt arrived in refrigerated liquid form and were stored at 4 °C until analysis. Brand A was refrigerated at 4 °C and rehydrated prior to analysis as recommended on the label. This was done with DNA-free water to avoid foreign bacterial contamination.

Two of the companies did not make a CFU claim, One company only claimed one million CFUs. The other three companies claimed 5 billion, 10 billion, and 15 billion respectfully. The researchers tested 2 different lots for each brand. They tested them on day 1 and day 14.

The Results of the Study

Day 1

No Company got even close to their claimed CFU. Even giving them the benefit of the margin of error only one company reached over a billion CFUs and they made no CFU Claim. The other brands products topped out at 301 Million even with giving them the margin of error.

Day 14

One batch increased in the number of CFUs. All other batches saw a significant reduction in CFUs. If you give them the benefit of the margin of error one batch got a little over 4 billion. The other lot however was nowhere close. The other brands topped out at 135.5 Million CFU’s This is a far cry from the claims of 10 and 15 billion.

My Commentary

Based off of my reading of the study they went off of CFUs per gram. One of the companies uses CFUs per ounce on their website and CFUs per gram on the label. One of the brands does list CFUs per ounce on the label. This could have been a significant oversight by the researchers, but also the company. I have contacted the researchers and the company to see what they say. This however doesn’t change the end result. Based off of my math both brands would still be very far off even when giving them the benefit of the margin of error.

End of Commentary

They all did worse than the yogurt you can buy from any grocery store that was analyzed as reference.

The second issue they found was in the strains of bacteria found versus those claimed on the label. In all of the products they found several strains of bacteria that were not listed on the label. Furthermore in some of the products the bacteria they claimed was not actually detected.

The results suggest a lack of quality control, accurate testing, and/or deficiencies in bacteria stability during storage. Even if label claims were met at the point of manufacture, viability should be maintained until the expiration date is reached.

The brands all make a variety of health claims. Most of the health benefits that they claim have only been demonstrated on humans, studies need to be conducted on animals.

My Commentary

I don’t have as much of an issue with discussing potential health benefits as long as they are saying potential. I would like for more research to be conducted, but I know that there is a limited amount of research money available, and certain things need to take priority. That being said the best that can be done is to hypothesize and rely on research that has been conducted on humans, and possibly anecdotal evidence from consumers. However three of the companies are fairly large. They most likely have the resources to actually conduct research if they wanted to validate their claims.

End of Commentary


The Authors of the study did say that the identification of Enterococci and Leuconostoc genera by was extremely low. This could mean poor survival, potential bias in the DNA extraction procedure, or limitations in the primers used for sequencing. Its possible that sonification might have broken up cell clusters better to provide a more accurate enumeration of bacteria. They do say more tests need to be conducted. Many bacterial species not claimed by the kefir labels were detected in sequencing, suggesting those species might originate from the manufacturing process and were not inadvertently listed, or misidentified by SILVA132 data base due to high sequence similarity with other species. For example, Lactobacillus casei and L. paracasei have very similar 16S rRNA sequences and may lead to misidentification when only one of these is present in the sample such as with products A, B, and YOG. Some labels had the issue of inconsistency in labeling bacterial genera and species properly, while others had issues with correct spellings and proper capitalization.


This is very concerning, and our pets deserve better.


Only one the companies that I contacted was transparent and for all intent and purposes admitted fault. They relaunched their product with updated process for quality control and labeling of the cultures; it remains to be seen if these changes fix the problem.

The other company that prides itself on transparency only had excuses. They at first claimed they had not seen the study then, later on, claimed that they didn’t think the study was going to be published. Some influencers jumped to the companies defense saying it is unreasonable to hold these companies to such high expectations. Those influencers obviously didn’t actually read the study. The company did address the fact that there were strains not listed and that is because they use raw milk. I pointed out to the company that their label says CFU’s per gram while online, during Facebook lives, and Youtube videos they say CFU’s Per Ounce. I was told they will be changing the label I am unsure when that change will occur, however. This occurred over the course of several emails with the person (Nutritional Science Director) who is essentially the face of the company.

Metras, Breanna & Holle, Maxwell & Parker, Valerie & Miller, Michael & Swanson, Kelly. (2020). Assessment of Commercial Companion Animal Kefir Products for Label Accuracy of Microbial Composition and Quantity. Journal of animal science. 10.1093/jas/skaa301.