Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose

Moldy Corn Toxicity

Synonyms: Blind, Sleepy or Mad Staggers, Corn Stalk Poisoning, Fumonisin Toxicity, Leukoencephalomalacia


This is an often fatal neurologic disease that results when a horse ingests corn that contains molds producing the potent toxin fumonisin. This toxin cause damage or death to living tissue (necrosis) in the brain and sometimes the liver. Horses usually only show signs of neurologic disease after eating corn containing fumonisin over a period of 2-9 weeks.

Keep in mind that this disease may be indistinguishable from rabies. Handle horses showing signs of neurologic disease only under your vet's guidance.

Diagnosis requires a compatible history of consumption of infected corn coupled with signs of severe brain disease. Often, more than one horse in a group is affected. Feed toxicologic analysis typically shows that corn contains a significant level of the fumonisin toxin. Post-mortem examination of horses shows destruction (liquefaction of white matter) of a specific area of the brain.

There is no treatment, although supportive nursing care is often instituted.

my vet's role



Other conditions or ailments that might also need to be ruled out by a vet.

Very Common
Less Common
more diagnoses


Grave. Once signs start, there is already destruction of the white matter of the brain. There is no known treatment, and recovery is rare.

my role


I might observe

You might make these observations when a horse has this condition.

Very Common
Less Common
more observations

Questions To Ask Your Vet:
  • What management changes can I make to prevent this from happening again?
  • Can the feed be tested for this toxin in order to prove this diagnosis?
  • How do you know my horse suffers from this disease and not rabies?

Do not feed horses moldy corn, cracked corn, or corn screenings. If feeding corn, always inspect it carefully before feeding. Particularly be on the lookout for screenings, which are small partial kernels, with visible dust or mold. Purchase high quality feeds for your horses. Do not stockpile feed or store it for a long period of time before feeding it and pay attention to the expiration date on all feed bags. If you ever wonder about the appearance of grain containing corn, do not feed it.

Fumonisin levels may be higher in corn that was drought stressed during growth and harvested during humid or wet periods.

further reading & resources


Outside Resources


Related References:

Lavoie JP, Hinchcliff KW eds. Blackwell's 5 Minute Vet Consult: Equine. 2nd Ed. Ames: Wiley Blackwell 2008.

Author: Doug Thal DVM Dipl. ABVP