Fumonisin B1 Concentrations in Feeds from 45 Confirmed Equine Leukoencephalomalacia Cases

Abstract

During the fall of 1989 and winter of 1990, numerous reports of equine leukoencephalomalacia (ELEM) occurred from many regions of the United States. Typically, horses were consuming feed partially or entirely composed of corn and/or corn screenings. From October 1989 through May 1990, samples from 55 confirmed or suspected ELEM cases were received at the National Veterinary Services Laboratories, Ames, Iowa, for fumonisin B₁ analysis. Samples from 9 cases in 1984–1985 were also obtained. Fumonisin B₁, a mycotoxin produced by Fusarium moniliforme, causes ELEM, but little is known of naturally occurring toxic or safe levels in feeds. To determine what levels of fumonisin B₁ in feeds are associated with ELEM, 45 selected cases were studied. The fumonisin B₁ concentrations ranged from 35 days. Horse feed samples not associated with ELEM were also collected and analyzed. None of the nonproblem feed samples contained fumonisin B, levels >8 ppm.