Abstract.A study to evaluate the effects of dietary fumonisin B, was conducted using 6 ponies (4 test and 2 control). A ration naturally contaminated with fumonisin B, was fed in 3 phases: 1) 44 ppm fumonisin B 1 , 2) less than 1 ppm fumonisin B 1 , and 3) 88 ppm fumonisin B,. All ponies were monitored daily, weighed weekly, and limit fed at a rate of 0.8% body weight plus hay. Feed intake was measured daily, and a serum chemistry panel was completed once or twice weekly. Four to 7 days after initiation of the trial (Phase l), all 4 test ponies had decreased feed consumption, and selected serum chemistry parameters were markedly elevated. On day 9, 1 pony died acutely with mild encephalopathy and hepatic necrosis. Another pony, euthanized on day 45, also had mild encephalopathy and hepatic necrosis. The remaining 2 test ponies continued the 44 ppm fumonisin B, diet for 98 days. Phase 2 consisted of a diet with < 1 ppm fumonisin B, for 120 days. During this phase, the serum chemistry values of the 2 ponies returned to normal. Following Phase 2, the 2 ponies were fed a diet containing 88 ppm fumonisin B 1 . After 75 days, 1 animal died of equine leukoencephalomalacia with mild hepatic necrosis. On day 78, the remaining pony was euthanized after showing distress; it also had leukoencephalomalacia and hepatic lesions.Equine leukoencephalomalacia (ELEM) has been recognized since the mid-1800s and has long been associated with the ingestion of corn contaminated with Fusarium moniliforme. Recently, fumonisin B 1 (FB 1 ), a mycotoxin produced by F. moniliforme, was shown by IV injection 8 and oral dosing 6 to produce the disease. The dramatic clinical signs and extensive brain lesions, in both natural and experimental cases of this disease, have resulted in numerous reports on the neurological syndrome but with little emphasis on the hepatic syndrome. [1][2][3][4][5][6][7][8][9][10]13 The present study was designed to study both the brain and liver effects from consuming a diet naturally contaminated with fumonisins and to provide information to help determine safe feed levels. The ponies were conditioned for 21 days on a control diet prepared as described above without CS. During the conditioning period and through day 12 of the trial, all ponies received 400-600 g of alfalfa hay per day. After day 12, hay was offered free choice. The ponies were housed and fed separately, and unconsumed rations were recorded daily.
Materials and methods
ExperimentalExperimental trial. The animal care and use protocol was reviewed by the National Veterinary Services Laboratories Animal Care and Use Committee, and the experiments were conducted in accordance with NIH publication No. 88-23, 1985. Six clinically normal ponies of both sexes and various ages were divided into the test and control groups (Table 1). Male and female ponies were present in each group. The ponies were observed daily. Weights, body temperatures, and the following serum constituents were measured d at periodic intervals: total bilirubin (BT), direct bilirubin (BD...