Diagnosis > Equine

Horses are the species most sensitive to feed borne fumonisins, which are found in maize and are produced by the Fusarium moniliforme. Fumonisins were first described relatively recently in 1988, and the most abundant is fumonisin B. There are three common fumonisin B mycotoxins, FB1, FB2 and FB3.  Fumonisins have a structure similar to sphingoid bases (i.e. sphingosine and sphinganine), which are components of sphingolipid molecules, and can can inhibit sphingosine-sphinganine-transferase and ceramide synthase (Wang et al. 1992). FB1 can cause equine leukoencephalomalacia ELEM (commonly called mouldy corn poisoning or hole in the head disease) in horses and once neurological clinical symptoms appear the condition will mostly be fatal. FB1 at a concentration of 10ppm has been found to be associated with ELEM. The clinical signs associated with the neurological form include apathy, drowsiness, pharyngeal paralysis, blindness, circling, staggering, seizures and eventual recumbency. Death usually follows within 2-3 days. There are no specific blood biochemical or haematological alterations in ELEM. The increase in haemoglobin concentration, packed cell volume, haematocrit and blood liver enzyme activities are characteristic of fumonisin-induced ELEM. Confirmation of death from equine leukoencephalomalacia requires veterinary examination of the horse’s brain for pathological features such as softening of brain tissue.  Other features include malacia, bile stasis and bile duct proliferation (Uhlinger, 1997). Outbreaks of ELEM occur sporadically from late autumn to early spring. Maize or corn screenings can be heavily contaminated and so should not be fed to horses at all.

Intervention level.
Concentrations of 5ppm FB1, FB2, FB3 or higher can cause colic and even death in horses and so feed containing 5ppm should not be fed to horses.  Maximum Fumonisin level is therefore 5ppm and maize screenings should never be fed to horses.