A mycotoxin produced by species of Fusarium fungus principally affecting corn (maize) and cause of mouldy corn poisoning. The fungus grows in the maize kernels before harvesting, often during a period of wet humid weather especially if that follows dry conditions. Affected corn kernels are discolored, pinkish to black.
Horses consuming corn containing Fumonisin can be affected by as little as 8-10 ppm if fed for a prolonged period. Toxicity relates to liver damage and leucoenchepalomalacia, liquefaction of the white matter of the brain. Symptoms include depression, drowsiness, head pressing, blindness, staggering gait, circling, facial paralysis, recumbency, coma and death. Yellowing of mucus membranes may be present (icterus) as a sequel to liver damage. Recovery is uncommon and horses which do recover may be left with neurological damage. There is no treatment for leucoenchepalomalacia but horses with only mild symptoms of liver damage may recover with supportive treatment.
The above notes are drawn from Dalefield, Veterinary Toxicology for Australia & New Zealand 2017