The U.S. Food and Drug Administrationís Center for Veterinary Medicine has issued a warning to horse owners about a toxin called fumonisin that can be found in corn or corn byproducts. A number of horses die each year from eating products that contain the toxin. Fumonisins are produced by an endophytic mold found in corn kernels, typically when the corn plant is growing in the field. Levels of the toxin can increase after harvest if put in improper storage conditions.
The danger from ingestion of the fumonisin toxin is dose related, and can cause leukoencephalomalacia in horses, which is a fairly uncommon but deadly neurological disease. FDA recommends that corn screening not be used in horse feed because they are involved in most of the investigated cases of fumonisin poisoning.
In order to prevent the levels of fumonisin and other mold toxins from increasing, corn and feed that contains corn needs to be kept dry and protected from moisture when stored. FDA recommends that corn and corn by-products used in horse feed should contain less than 5 parts per million (ppm) of fumonisins and should make up no more than 20 percent of the dry weight of the total ration.
More information on fumonisin levels in feeds, including the official FDA warning, can be found on the following websites: