THE 1ST CASE OF EQUINE MOTOR-NEURON DISEASE IN JAPAN

A 9-year-old male horse showed emaciation, weakness and trembling and was euthanatized. Histopathological examinations revealed loss, swelli ng and chromatolysis of motor neurons throughout the spinal ventral ho rns, axonal degeneration of the ventral spinal roots. Eosinophilic cyt oplasmic inclusions were distributed in degenerated spinal ventral neu rons. Ultrastructurally, the inclusions consisted of aggregations of g ranular dense material and a few vesicles. They reacted positively wit h polyclonal antibody against ubiquitin. The present case was diagnose d as equine motor neuron disease, which has recently been reported in North America and the United Kingdom.