Safety of Nutritional Supplements for Horses Unknown, Researchers Say

Just because a supplement comes in fancy packaging with a tamper-resistant foil seal and promises of efficacy does not necessarily mean that it is safe for your horse.

According to the Committee on Examining the Safety of Dietary Supplements for Horses, Dogs, and Cats, sponsored by the Center for Veterinary Medicine of the Food and Drug Administration (CVM-FDA), a comprehensive adverse event reporting system is needed to record important details of supplement exposure including dose, active ingredient, and disease characteristics. Further, the committee recommends that this data should be available to the public.

At present, veterinary nutritional supplements, defined by the Committee as "a substance for oral consumption by horses, dogs, or cats, whether in/on feed or offered separately, intended for specific benefit to the animal by means other than provision of nutrients recognized as essential, or provision of essential nutrients for intended effect on the animal beyond normal nutritional needs, but not including legally defined drugs," are not manufactured like human nutritional supplements or pharmaceutical drugs and no system to report, record, or evaluate supplement safety currently exists.

To address this issue, an eight member committee was created to examine published scientific reports to evaluate whether feeding lutein, evening primrose oil, or garlic to horses, dogs, or cats was associated with any significant adverse health effects that resulted in changes in the normal function of supplemented animals.

Evaluation of efficacy claims was not part of this study. Instead, the goal of this project was to "form the basis of a more general framework for evaluating animal dietary supplement safety."

The committee reported that insufficient safety data exists for supplements, even when compared to those normally required for animal drugs and animal food additives.

In the 313-page report, the committee also indicated that they would have liked to have had the data to define a "no observed adverse effect level" (NOAEL), or at least a "safe upper intake level" (SUL), for each of the three examined supplements, but the data is simply not available.

According to the committee's report, "because most ingredients in animal dietary supplements are not proprietary substances, it is unlikely that the amount of target animal data will ever be sufficient for safety assessment, and research findings in other species provide important evidence about safety."

While this latter point is true for many products, some manufacturers of nutritional supplements voluntarily utilize current Good Manufacturing Processes (cGMP), which means that their supplements are produced using the same quality standards as pharmaceutical drugs.

Another important take home message from the report is that that safety of a supplement in humans does not guarantee safety in animals.

"Safety is, of course, very important to assess in the target species," said Barbara Eves, DVM, senior manager of scientific communications of Nutramax Laboratories, Inc. located in Edgewood, Md., who commented on the study. "We support the development of safeguards/regulations to ensure the safety and quality of dietary supplements for animal use."

The report, "Safety of dietary supplements for horses, dogs, and cats," is available by contacting The National Academies.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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