Equine Fescue Toxicosis Fescue Toxicosis in Horses Equine fescue toxicosis is caused when pregnant mares eat tall fescue that is infected with an endophyte fungus, Acremonium coenephialum . Both the mare and the foal can be affected when the mare eats endophyte-infected fescue. All is not lost if your broodmare eats endophyte-infested fescue.
Treatment is available, although prevention is the best protection.
The endophyte, Acremonimum coenophialum, grows symbiotically with tall fescue. It is similar to the ergot fungus although A. coenophialum is evolutionarily derived from Epicloe typhina . This fungus is the reason for some of the advantages of fescue, such as insect resistance. However, it is also the cause of the toxicity. The major alkaloid produced is the indole alkaloid, ergovaline.