Mycotoxins in the Equine Environment

Mycotoxins are compounds produced by molds and fungi, and can be found in pastures as well as on dried forages, bedding, grains, and complete feeds. Of all the agricultural species, horses are among the most sensitive to toxicosis from mycotoxins. An important reason for this is that horses typically have a much longer lifespan than any other agricultural species and exposure to mycotoxins can take place over many years.

Clinical signs of pathological exposure to mycotoxins may include reduced growth rates in foals and young horses, respiratory dysfunction, problems with fertility and reproduction, neurological and/or brain disorders, liver or kidney damage, allergic reactions, anorexia, reduced performance, and colic.

Pastures and forage

The type and magnitude of reactions to mycotoxin exposure can vary widely, depending on many factors. These include duration of exposure to the toxin (repeated exposure to low-dose toxins can result in greater sensitivity), previous toxin exposure (single bouts of toxicosis lead to intensified reactions during subsequent exposures), age, breed, workload, immune and nutritional status, and type of toxin to which the horse is being exposed. Furthermore, if the toxins are being delivered in contaminated feed, there is frequently more than one type of toxin present. This often leads to synergistic toxicities, amplifying toxic effects of individual compounds.