The chemical Phenibut has been banned from United States Equestrian Federation (USEF) competitions. The name of the chemical, Phenibut, is similar to the drug phenylbutazone―and I am sure this is to make horse owners think it is the same chemical―but they are not. The USEF has a drug and medications program that carefully watches products and product claims that are used in horses, and they say Phenibut is considered a foreign substance. The chemical was recently found in a product called Focus Calm and is also available as a single substance, but it is not considered legally to be a drug. There are no known scientific studies documenting its safety in horses and there is no legitimate therapeutic purpose for this substance to be used in horses.
Owners of the many horses that participate in USEF competitions may be unaware the chemical is forbidden as there are thousands of equine supplements on the market that may contain almost any chemical. The USEF indicates any of the calming supplements that are intended to alter a horse’s behavior should be regarded with scrutiny when used in competition horses.
Even if your horse does not compete in USEF events, it is not a good idea to use these unproven and potentially dangerous chemicals that are in many of these supplements. The USEF wants to remind members that the names of the substances included on a supplement’s list of ingredients may not always be associated with a forbidden substance and yet could be in there and cause your horse to be disqualified. There is a lot of variability in the substances listed on the labels of these supplements, so be careful using anything that indicates it will have a calming effect on your horse, regardless of what is on the label.