Equine motor neuron disease in a Jeju pony

Equine motor neuron disease (EMND) is a spontaneous neurologic disorder of horses, which results from the degeneration of motor neurons in the spinal cord and brain stem. An 8-year-old Jeju pony gelding presented with weight loss, muscle tremors, frequent recumbence, low head carriage, sweating, and standing with four limbs close together. The gelding has been on the same stable and limited access to pasture for several years. The gelding has been fed with dried hays and commercial concentrated feeds. Laboratory test revealed very low serum vitamin E level (0.14 μg/mL; reference range > 1.5 μg/mL), mildly elevated creatine kinase (402 IU/L; reference range 119-287 IU/L) and aspartate aminotransferase (876 IU/L; reference range 226-336 IU/L). Oral glucose absorption test showed decreased glucose absorption. Histopathologic examination using a biopsy specimen from sacrocaudalis dorsalis medialis muscle revealed atrophic and hypertrophic muscle fiber, centralization of nucleus, degenerating and necrotic muscle fibers. Taken together, the gelding was diagnosed as EMND. After oral vitamin E administrated for 5 weeks, the gelding showed normally improved stance, decreased periods of recumbency, improved head carriage and weight gain except consistent tremors. This is the first report that successfully treated EMND case occurred in a Jeju pony in Korea.