Fumonisin B₁ Levels Associated with an Epizootic of Equine Leukoencephalomalacia

Abstract

During the fall of 1989, an episode of equine leukoencephalomalacia involved 18 of 66 purebred Arabian horses at a breeding/training stable in Arizona. Of the 18 horses affected, the condition was fatal in 14. These horses, as well as 48 unaffected horses, had been fed a diet containing a substantial amount of white corn screenings. Gross pathologic findings included liquefactive necrosis in parts of the cerebral white matter and hemorrhagic foci of various sizes in the brain stem. Histopathologic findings included rarefied white matter with pyknotic nuclei and eosinophilic cytoplasm. Thin-layer chromatography, high-performance liquid chromatography, and gas chromatography/mass spectroscopy were utilized to identify and quantitate fumonisin B1 in 3 samples of corn from the farm. Concentrations of fumonisin B1 range from 37 to 122 ppm. Fumonisin B2 was also detected. Using information on diet, animal weights, and feeding practices, estimates of total fumonisin B1 dosage were determined. This is the first definitive report on equine leukoencephalomalacia and associated fumonisin B1 concentrations.

A Rapid, Sensitive Thin Layer Chromatography Procedure for the Detection of Fumonisin B1 and B2

“…Washing the column with acetonitrile : 1% aqueous KCl (9:1) removed a number of matrix interferences and allowed the fumonisins to be quantitatively eluted with acetonitrile : water (7:3). 13 Overall recoveries of fumonisin B 1 and B 2 added to corn at concentrations ranging from 5 to 200 ppm averaged >80% using this procedure. Fumonisin B 1 and B 2 were readily resolved by reverse-phase TLC with methanol : aqueous 4% KCl.…”

“…These levels were confirmed by HPLC analysis. 13 Fumonisin B 2 was observed at low levels in some samples, but no attempt was made to measure its concentration. At the Barton County location, 43% of the corn samples had detectable levels of fumonisin B 1 , whereas at the Boone County site, only 3% of the samples had detectable fumonisin B 1 .…”

“…Fumonisin B 1 and B 2 were quantitated by HPLC using a modification of a previously described procedure 13 for spike recovery studies and confirmation of corn survey samples. The fluorescamine derivatives of fumonisin B 1 and B 2 were prepared by treating 100 µl of the eluant with 100 µl of borate buffer (0.1 M, pH 8-9) followed by 100 µl of fluorescamine (0.4 mg/ml in acetonitrile) in a 1-dram brown glass vial.…”

“…12 Recent studies have shown fumonisin B 1 to be responsible for equine leukoencephalomalacia (ELEM) 5,6 and swine pulmonary edema. 3 In the United States, fumonisin-contaminated corn screenings have been associated with cases of ELEM [7][8][9]13 and swine pulmonary edema, 3,9 but only limited information is available on natural occurrence and levels of incidence of the fumonisins. A number of analytical procedures for fumonisins in corn and corn products, including thin layer chromatography (TLC), high performance liquid chromatography (HPLC), and gas chromatography/ mass spectroscopy (GC/MS), 8,10,12,13 are available, but all are of limited value or not readily available for extensive monitoring of fumonisin contamination in corn.…”

“…The procedure was a modification of a previously described method. 13 Fifty grams of finely ground sample was placed in a widemouth polypropylene screw-cap bottle with 100 ml acetonitrile : water (1: 1) and placed on a wrist-action shaker b for 30 min. The contents were allowed to settle, and a 10-25 ml aliquot of the solvent extract was decanted and filtered.…”