Three marketers of equine drugs have been warned by the US Food and Drug Administration (FDA) this week, all for allegedly marketing their products without first receiving approval from federal regulators.

The three companies—Tri-Star Equine, HorsePreRace and Horse Gold, Inc—are all accused by FDA of marketing their products in ways that cause them to be "intended for use in the mitigation, treatment or prevention of disease in animals." As with their human equivalents, marketing products in this way causes them to fall under the Federal Food, Drug and Cosmetic Act (FD&C Act) and to be defined as drug products.

All three companies reportedly marketed drugs intended to treat ulcers—a common ailment in horses, and especially racehorses.

The problem, FDA says in the three separate Warning Letters, is that none of the companies sought approval from FDA for their respective drugs prior to marketing them to the public. By failing to obtain proper regulatory approval from FDA, the companies' drugs were both adulterated under Section 501(a)(5) of the FD&C Act and considered "unsafe" under Section 512(a)(1).

FDA also sent a fourth Warning Letter regarding similar allegations to a marketer of an unapproved canine oncology drug.

All four companies were ordered to immediately comply with FDA's Warning Letters and respond to FDA within 15 days regarding the status of their compliance.