Last fall, a cluster of horse deaths were linked to feed tainted by small amounts of monensin, an antibiotic sometimes fed to cattle that’s toxic to horses.

Though the feed contamination was limited, the incidents caused owners to wonder how they could ensure their horses’ feed was safe. And, while it’s all but impossible to ensure that every batch of every horse feed—or most any food product, for that matter—is safe, the U.S. Food and Drug Administration (FDA) is implementing a new rule that will help put feed safety odds in animals’ favor.

"Feed companies make efforts to ensure that their products are safe," said Nettie Liburt, MS, PhD, PAS, of Liburt Equine Nutritional Consulting, in Long Island, New York. "Testing protocols may vary slightly from manufacturer to manufacturer, but the bottom line is that no company wants to put a contaminated or unsafe product on the market."

Liburt explained that according to the American Feed Industry Association (AFIA), each facility that manufactures animal feed must be registered with the FDA, and ingredients those facilities use in their products must be considered “generally regarded as safe” by the FDA