Equine Leukoencephalomalacia (ELEM)
By Drs. Giselle Cino, Mike Moore, Jonathon Sago and Jeffrey Laifer
Equine Leukoencephalomalacia is caused by the ingestion of moldy corn. The cerebral changes are caused by fumonisin compounds produced by Fusarium spp., a fungus that grows on corn grains. There are several different fumonisin compounds, however B1 is most commonly associated with ELEM.
Clinical History and Physical Examination Findings
An adult Appaloosa gelding was presented for gross necropsy. The night before, this horse had become ataxic, and was found dead the next morning. This horse was in a herd being fed grass hay and whole corn which was reported by the owner to be “slightly” moldy. At the request of their veterinarian, the owners had stopped feeding the moldy corn 3 weeks previous because another horse had presented with ataxia and blindness. Unfortunately, they began feeding the corn again, one week previous to the case reported here.
On necropsy, the only tissue affected was the brain. There was right-sided cerebral edema, yellow gelatinous malacia and liquefaction within the frontal, parietal, and temporal lobes. The areas of malacia spared the gray matter. Mild hemorrhage was present within the necrotic white matter. (Figure 1)
See Figures 2 and 3 (right column).
Rabies testing was negative.
Take Home Message
Equine Leukoencephalomalacia caused by ingestion of fumonisin can lead to severe neurological signs and death of multiple horses. Toxicity level and lesion severity depend on dose and length of time that horses are exposed to the affected feed; they are typically present 1-2 days after exposure. However, clinical signs may take weeks to develop occasionally. Clinical neurologic signs will depend on the severity of lesions and the anatomic locations most heavily affected. As there is no treatment for this condition, prevention measures are important and dependent on not feeding molding corn to horses.
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