GILMAN, Minn. (WCCO) – The Food and Drug Administration is investigating a single batch of horse feed from Gilman Co-Op Creamery in Gilman that has killed six horses.

The FDA found the feed to contain monensin, an animal drug highly toxic to horses, even at low levels.

Following an inspection, the FDA found that the batch of horse feed linked to the deaths was mixed after the creamery mixed cattle feed containing the drug. The creamery did not perform adequate clean out to remove the monensin from its equipment before mixing the horse feed.

Though the feed was a special order for a particular farm and not distributed elsewhere, the FDA wants to make manufacturers and horse owners aware that monensin in horse feed is a continual concern.

Horses exposed to the drug may show symptoms including weakness, unsteady gait, inability to get up, diarrhea, abdominal pain, excessive urination, heart failure or death. The toxin may also progress rapidly enough to kill the horse without obvious symptoms.

The investigation regarding the horse feed case is ongoing, and the FDA will take action as appropriate.