BATON ROUGE, La. — A fatal brain condition of horses caused by fumonisin mold toxins in the corn they are eating is a potential problem for horse owners, veterinarians and feed suppliers, according to LSU AgCenter veterinarian Dr. Steven S. Nicholson.
Nicholson said suspected cases have been seen recently but not yet confirmed.
"Diagnosis of the condition, known as equine leucoencephalomalacia (ELEM) or moldy corn poisoning, requires examination of the brain by a veterinary pathologist," Nicholson said.
Other potential causes for similar symptoms are viral encephalitis, including rabies, and liver failure, the LSU AgCenter veterinarian said.
"ELEM is an old problem that can still cause significant loss of horses," Nicholson said, adding, however, that there are tests that can help to stem the problem — by determining the level of fumonisins in corn.
"Conditions prior to harvest of Southern corn were favorable for the fusarium fungi, which are capable of infecting corn and producing toxin in the field," Nicholson said, adding, "Toxin production may continue in stored corn if moisture content is optimum."
Cases of the problem tend to occur after the animals eat corn or feed made with corn containing toxic levels of total fumonisins. The U.S. Food and Drug Administration published guidelines for use of corn containing fumonisins, and more details on those can be found at www.cfsan.fda.gov/%7Edms/fumongu2.html.
"Corn containing levels above 1 part per million should not be fed to horses (equids) or rabbits as the sole grain diet," Nicholson cautions, adding, however, "Corn containing up to 5 ppm fumonisins may be added to horse feed, but the feed must not exceed 1 ppm."
ELEM in horses develops after the animals consume the toxin for several days or weeks.
"When the condition develops, there is a sudden, unexpected onset of neurologic signs such as tremors, complete or partial blindness, wild running and violent behavior," Nicholson said. "There is no effective treatment, and death often follows within hours."
Cases may develop up to two weeks after the last feeding of toxic material, according to Nicholson, who says where some horses have died of ELEM, other horses may appear to be normal but have evidence of liver damage caused by fumonisins.
Rabbits and swine are at risk of poisoning, but cattle are more resistant, Nicholson said, stressing, "Feed corn should be tested for fumonisins and another mold toxin called aflatoxins."
Tom Merrill is News Editor for LSU AgCenter Communications.