Moldy Corn Toxicosis in Horses

Here are some of the symptoms you will likely see in your equine if moldy corn toxicosis is present:

• Apathy
• Drowsiness
• Pharyngeal paralysis
• Blindness
• Circling
• Staggering
• Recumbency even to the point of not being able to get up
• If the liver is involved, jaundice will likely be noted as well

These symptoms indicate some brain involvement, making this syndrome very serious for your horse. Corn is not the only grain which can become infected with this fungi; oats and barley are a couple of others which are harvested and packaged under wet or humid conditions, lending help in the development of the fungi and later the toxin.

Types

There is only one type of moldy corn toxicosis in horses. This mycotoxin-related syndrome is prevalent in horses and pigs predominantly, with other grain-eating mammals tolerating more of the toxin than horses and pigs. As noted above, moldy corn toxicosis affects the liver and the neuro system of the horse as it progresses. The deterioration that is causing the symptoms is taking place in the brain and, once the neurological symptoms present, the prognosis for the horse is not good.

There are literally dozens of fungi which can infect corn, oats and barley and this is especially so when they are processed and packaged under humid conditions. 

• A toxin called fumonisin is produced by the fusarium fungi and this toxin causes problems in the liver as well as neurologically when it is eaten in sufficient amounts over a period of time
• Signs and symptoms can begin to present within a day or two or it may take a couple of weeks 
• The corn doesn’t look or smell different when the fungi is present so the horse just keeps eating and eating, building up the toxin in its system

• As the amount of toxin builds up in the horse’s system, the symptoms noted above begin to be displayed with the more serious ones being the neuro symptoms - generally, once the neuro symptoms show up and the horse goes down and is unable to get up, death comes in 1 to 2 days

That prevention of moldy corn toxicosis in horses is paramount should be pretty obvious by now. This disease is fatal for those horses in whom the disease progresses to the stage at which the neurological symptoms are being exhibited. For some horses, this stage of the disease comes rapidly, perhaps in terms of hours rather than days or weeks. Avoiding the feeding of corn is one mode of prevention but also let’s consider that other grains also can contain the toxin so having a no risk situation is not likely. So what do you do?  

• Feeding top quality corn that is processed and evaluated by commercial feed mills is one way to reduce the risk
• Try to feed your corn supply to your horses within two weeks of purchase, especially when it is hot and humid
• Be sure to trash any feed that has gotten wet or that has been around for longer than 6 weeks in the hot, humid summer season

• Educate yourself and all those who come into contact with your herd on the earliest symptoms of moldy corn toxicosis - getting your vet involved sooner rather than later could be the difference between recovery and death