Approximately 70 feeder pigs developed ataxia and other signs of neuromuscular dysfunction. The ration fed the pigs was found to be contaminated with Cassia occidentalis seeds. Experimentally, other feeder pigs were fed this ration, and they developed ataxia and other signs of neuromuscular dysfunction within 6 to 8 weeks. In further experiments, feeder pigs fed diets containing 1%, 2%, or 4% ground cassia seeds also became intoxicated. Microscopically, diaphragmatic myopathy and pancreatic tissue necrosis were the principal pathologic findings.