Can they eat it? / Moldy corn (fumonisin)
Can horses eat moldy corn (fumonisin)?
Never. Causes a fatal brain disease.
Mouldy corn and corn screenings carry fumonisin, which destroys brain tissue (moldy corn poisoning). Any corn with mould or an off smell goes in the trash, not the feed tub.
Pressing the head on walls, circling, blindness, stumbling, death.
Call your vet now. Note what was eaten, how much and when; do not wait for signs.
Why it is dangerous
Moldy corn carries fumonisins, toxins made by Fusarium mould that grow when corn is damp, stored warm, or harvested wet. Fumonisin disrupts sphingolipid metabolism in the brain and liver, which destroys brain tissue and causes the disease called equine leukoencephalomalacia. The mould often doesn't look obvious, and corn screenings and dusty feed can be just as contaminated as whole kernels. Any corn with visible mould, a musty or sour smell, or clumped kernels should be thrown out.
How much is too much
There is no safe amount of moldy corn for a horse. Even a small quantity can contribute to serious harm, and a large amount can cause fatal brain damage. This applies equally to a 1,000 lb horse, a pony, a miniature, or a senior. Because the damage is progressive and can show up days later, any suspected exposure should be reported to your veterinarian right away, however little was eaten.
Horses
Full-size horses in work or at pasture are often fed grain or given loose corn as treats or from spilled feed bins, so check every bag and bin before use. Store corn in a dry, ventilated place off the ground, and watch for condensation or damp spots in feed rooms. Keep horses away from spilled or moldy grain on the ground, and clear out old feed regularly so it doesn't get mixed back in.
Ponies and easy keepers
Ponies, miniatures, seniors, and easy keepers are just as vulnerable to fumonisin, and their smaller body size makes any exposure more concerning. Be especially careful with corn-based treats, since those are easy to overfeed and hard to check. Keep these horses on a feeding plan you control, and don't let them access grain bins or spilled corn from other horses.
Safe alternatives
Offer a fresh, clean hay as the main forage, plus a commercial pelleted or textured feed made for your horse's needs. For treats, try carrot pieces, apple slices with the core removed, or a small handful of plain oats. Always cut treats into small pieces and serve them in a safe, supervised way.
Questions people ask
Can moldy corn be in hay?
Corn is not normally part of hay, but moldy grain or feed can end up mixed into bedding or spilled into hay areas. Check all feed and hay for mould, and discard anything suspicious.
Is corn safe after a frost?
Frost and damp weather can encourage fungal growth in corn in the field or in storage. Check corn carefully after frost and throw out anything that looks mouldy or smells off.
My horse ate some moldy corn, what should I do?
Call your veterinarian now, even if the horse seems fine. Note what was eaten, how much, and when, and do not wait for signs to appear before getting help.
Toxic for horses means: do not give it; if they ate it, call your vet or a poison line.
General information from veterinary guidance, not a diagnosis. If you are worried, call your vet or a pet poison line: ASPCA Animal Poison Control (888) 426-4435. Charges may apply.
Written by Hoofdeck editors · updated Nov 13, 2026 · from ASPCA Animal Poison Control, Merck Veterinary Manual and university extension guidance.