Tennessee Farmers Cooperative officials voluntarily recalled four lots of horse feed in early and mid-November after a horse’s death was linked to the feed, which contained high levels of a livestock drug. The 10% Grain Mix (item #93638) was contaminated with rumensin (monensin sodium), a common cattle drug.

John Niver, nutritionist at the Co-op, said, “Rumensin is typically for promotion of feed efficiency in beef cattle, and at certain levels for prevention of coccidiosis (a protozoan infection).” Niver said the Co-op is trying to determine how the rumensin got in the horse feed.

Monensin is particularly lethal to horses–a dose of just 1.0-3.0 milligrams per kilogram of equine body weight can kill more than 50% of the horses that eat it. Horses with monensin poisoning become progressively weak (especially in the hindquarters), uncoordinated, and disoriented, and they often develop colic, labored breathing, and profuse sweating before death. Horses that recover can experience long-term heart problems, unthriftiness, and poor performance.

The Co-op recalled four lots of the feed (4276593638, 4283593638, 4287593638, or 4290593638 printed on the back of the bags), which were distributed between Oct. 10 and Oct. 25, to five Co-op feed outlets in East Tennessee and one store in northeastern South Carolina. Only one lot (4287593638) is of major concern, Niver explained. There were about 123 bags in that lot, which were dispersed to three member Co-ops in Eastern Tennessee–McMinn/Loudon, Blunt, and Monroe Farmer’s Cooperatives