Formaldehyde. Pentobarbital. Oxytocin.

Those drugs are among an eye-raising list of medications that will not be allowed on show grounds with anyone except a veterinarian, under an extraordinary rule change proposed by the U.S. Equestrian Federation’s Veterinary Committee.

“There are no legitimate reasons for trainer, owners, riders, and grooms to have these substances on the grounds of a Federation Licensed Competition, and horse welfare is at risk,” the committee wrote when it submitted its proposal to add a new section to the “Prohibited Practices” section of USEF’s drugs and medications guidelines specifying substances that may not be used, or even be brought onto show grounds, by a non-veterinarian.

The list includes:

• injectable adrenocorticotropic hormone (ACTH)
• injectable adenosine
• injectable formaldehyde
• injectable magnesium sulfate
• injectable melatonin
• injectable oxytocin
• injectable pentobarbital (except by a veterinarian for the purpose of euthanasia)
• injectable thiamine
• injectable tryptophan
• liquid nitrogen

The rule change would also prohibit possession of any prescription medication without a label identifying the horse, pharmacy, prescription date and prescribing veterinarian, unless it is in the possession of a veterinarian.

“This extraordinary rule change was put forward because there is no therapeutic use for these substances on the show grounds in the hands of non-veterinarians,” Vicki Lowell, USEF chief marketing and content officer, wrote in an email. “Prohibiting the presence of these substances on show grounds further protects horses and helps ensure fair competition.”

Lowell confirmed the rule targets substances whose use and misuse have been reported to USEF.

“It has been reported that these substances are used in an attempt to gain a performance advantage in competition but could be detrimental and even potentially life threatening to horses and ponies,” she wrote.

While some of the medications on the list are generally known to have calming effects, Lowell did not specify what performance-enhancing benefits might be conferred by any of the chemicals on the list.

The Chronicle’s veterinary editor Dr. Joe Davis, DVM, said he was surprised by some of the named substances.

“The formaldehyde is a bit of a shocker,” he wrote. “That’s very poisonous, and there is no legitimate [systemic] therapeutic use in horses that are still alive.

“The formaldehyde, liquid nitrogen, and pentobarbital all fall under the category [of] no therapeutic use in current veterinary practice and [are] dangerous to use,’ ” he added, while also noting liquid nitrogen can “freeze fire” an area to temporarily kill sensation, and that pentobarbital—one of the chief drugs used in euthanasia—is a Schedule II barbiturate anesthetic “which shouldn’t be dispensed to anyone.”

The rule change is among a group of proposals, many of which are focused on safeguarding horse welfare,  that will be reviewed by the organization’s board of directors during the U.S. Equestrian Annual Meeting, held Jan. 23-25, in Lexington, Kentucky. While the proposal was first submitted in August, USEF called it out in an email to members this week focused on several of the upcoming rule change proposals the organization said are “aimed specifically at strengthening US Equestrian’s position on horse welfare.”

While the standard rule change proposals currently up for discussion will go into effect Dec. 1, 2026, if approved, extraordinary rule changes such as this one are considered pressing enough to undergo an expedited process. This rule would have a start date of April 1, 2025, if approved.

Rule changes can be viewed on the USEF website. For more information on USEF’s annual meeting, or to register to attend, click here.