It is common for horse owners and veterinarians to supplement horses with probiotics in an attempt to optimize intestinal microbiota. Many commercial products are available with varying label claims. A study at Washington State University College of Veterinary Medicine examined 11 commercial products to evaluate the content and inter-lot variation through the use of culture and PCR techniques [Berreta, A.; Burbick, C.R.; Slexander, T.; et al. Microbial Variability of Commercial Equine Probiotics, Journal of Equine Veterinary Science 2021, doi.org/10.1016/j.jevs.2021.103728].
Each of the 11 products randomly selected was purchased at least three times from the same source at least three months apart and evaluated before expiration. The products were stored in a cool, dry environment protected from light. Four products were pellets, one was a paste, and six were powders. In addition to culture, PCR was used to identify genomic DNA of dead or non-viable organisms to determine if they might have been originally present in the bucket.
The results are important to consider when recommending probiotic products:
- None of eleven products met their label claim of as many or viable microorganisms for all listed.
- Consistency in lots occurred in only three products based on culture and PCR.
- Microorganisms cultured or examined via PCR for DNA were lacking in five products.
The authors reported: “Discrepancies commonly persist between the label claim of probiotics marketed for use in horses and their actual content.” It is possible that manufacturing stresses, transportation and storage processes might significantly reduce microorganism viability to result in differences between label claims and actual content.
The bottom line is that label claims are not always supported by the contents of probiotic products, and there is a need for improvements in quality control.
