[Equine motor neuron disease: a review based on a case report].
A 10-year-old, non-pregnant Dutch Warmblood mare was referred to the Department of Equine Science because of chronic weight loss, despite good appetite, and dullness. Clinical examination revealed muscle atrophy, trembling of the limb muscles, an abnormal stance in which all four limbs were placed under the body, and an abnormal low head carriage. The plasma vitamin E concentration was markedly decreased (0.2 mumol/l), the electromyographic (EMG) examination was consistent with denervation, and the oral glucose absorption test was below the reference value (40% increase over the resting glucose level). Because of the clinical diagnosis of equine motor neuron disease (EMND), the horse was euthanazed and post-mortem examination confirmed this diagnosis. Based on the similarity in pathological findings, EMND can be compared to amyotrophic lateral sclerosis (ALS) in humans. However, in horses, only the lower motor neurons and occasionally some nuclei of the cranial nerves are affected. Because of the low plasma vitamin E concentration found in horses with EMND, an absolute or a relative antioxidant deficiency can be involved in the pathogenesis. In general, it is a progressive disease process and stabilization of the situation is the best feasible result. There is no specific therapy other than vitamin E supplementation and the prognosis is poor.