Stachybotryotoxicosis is a fatal hemorrhagic disorder of horses. It is caused by types of mycotoxins known as trichothecene satratoxins, produced by certain strains of Stachybotrys spp.. Stachybotrys are common saprophytes found in improperly dried or extended length of storage of hay and straw.

Horses become infected through ingesting the toxins when consuming contaminated hay or inhaling when sleeping or standing on contaminated bedding.