In the human and animal health realms alike, the dietary supplement industry is bigger than ever. A recent U.S. Government Accountability Office report showed the human market grew from approximately 4,000 products in 1994 to as many as 90,000 in 2017, and the horse supplement world has seen a similar explosion.  

It can feel easy to solve a problem (or mitigate well-intentioned anxiety about a health issue) by reaching for a supplement. Many people assume that a supplement can’t possibly hurt their horse management program, so it’s worth trying.  

What most owners don’t realize is that dietary supplements – human and animal – are not regulated by the Food and Drug Administration the way medications and food are.  

“I always tell people that when they’re using supplements, they’re doing so at their own risk,” said Dr. Stephen Schumacher, chief administrator of US Equestrian's Equine Drugs and Medications Program. “You’re relying on what the manufacturer tells you, and there’s no one holding them accountable.”  

Federally-approved, mass-manufactured drugs are required to undergo rigorous testing to ensure the composition of each batch matches what’s on the label, and that it doesn’t change from batch to batch. FDA-approved facilities are held to certain standards regarding the sourcing of their ingredients. Drug companies also go through intensive processes to prove a new product is safe and does what its makers claim it does. Dietary supplements aren’t required to do any of those things (although some may set up internal standards voluntarily).  

There are a few questions Schumacher suggests horse owners ask before putting their horse on a new supplement:  

• Where’s the research? Research is expensive; if a supplement maker has invested in research, they usually want consumers to be able to find it. Ideally, research should be peer-reviewed (meaning it has been published in an academic journal and scrutinized by independent researchers) and should be done on horses. While many substances have similar effects across species, others don’t, and horses’ body systems may be more or less sensitive than a human for certain substances. Schumacher wants to see documentation both of an ingredient’s efficacy and its safety. 
   
  “There’s a difference between testimonials and research,” he said. “Testimonials are not the same thing as peer-reviewed research.”  

• Does my horse need this? Thanks to the availability of commercially-mixed complete feeds, it’s rare for fit competition horses to be deficient in a nutrient. There are exceptions – electrolytes are given to replace minerals lost through sweat, and hay and pasture in certain geographic regions may be lacking in certain minerals – but many of those exceptions can be spotted by a veterinarian. Schumacher encourages owners and riders to consult with their vet before adding a supplement to a horse’s diet.  
   
  With the costs of horse ownership ever-increasing, it’s also worth asking yourself whether buying an unneeded supplement will take resources away from your budget that should be used elsewhere in your horse’s care. 
   

Most importantly though, Schumacher wants you to know that there are risks inherent in the use of dietary supplements in horses. Some supplements have been found to contain prescription drugs that weren’t on their labeling, which poses problems for horses whose caretakers don’t know what they’re dosing them with. Some vitamins and minerals can be harmful if given in large quantities, and others may interact negatively with each other when given together. 

From the perspective of USEF, you should also know that supplements can – and have – caused positive drug tests at horse shows. In 2017, two dressage horses tested positive for the FEI banned substance ractopamine in what was later found to originate from a contaminated gastric supplement they were given. That supplement was made by Cargill, which produces feed products for a variety of species. Ractopamine is a legal medication in cattle and swine, but is not permitted in horses. Earlier this year, an FEI tribunal determined a contaminated supplement caused a Trazodone positive in a horse on the Belgian Olympic eventing team. In 2013, a New Zealand eventing horse tested positive for reserpine after the Burghley Horse Trials; an FEI tribunal found the reserpine had originated from a liquid herbal supplement marketed to reduce stress in horses which was not advertised to contain the drug. 

Members are reminded that the discovery of a prohibited substance in a supplement after a positive test is not grounds for a dismissal of charges by USEF.  

“These examples are at the highest level of our sport,” said Schumacher. “If that happens to them, it could happen to anyone.” 

Learn more about how to prevent drug violations in this video from our USEF Learning Center.