Equine Neurology || Neurodegenerative Disorders

✍ Scribed by Furr, Martin; Reed, Stephen

• Publisher: Blackwell Publishing Ltd
• Year: 2007
• Tongue: English
• Weight: 390 KB
• Edition: 1
• Category: Article
• ISBN: 0813825199
• DOI: 10.1002/9780470376461.ch19

✦ Synopsis

EQUINE DEGENERATIVE MYELOENCEPHALOPATHY

History and Epidemiology

Equine degenerative myeloencephalopathy (EDM) was first reported by Mayhew 1,2 in 1976 as an acute to insidious onset symmetric ataxia and weakness of the trunk and limbs in 5 horses of various breeds as well as a captive zebra. The signs began as early as birth and as late as 12 months of age. Affected horses had diffuse degenerative changes in the spinal cord and brainstem with involvement of the cuneate, gracilis, and lateral spinal cord nuclei. Since the original description, EDM has been reported in the United States in a donkey 3 and in horses of the Thoroughbred, 4,5 Quarter Horse, 4,5 Standardbred, 2,4,5 Arabian, 5 Appaloosa, 6 Paso Fino 7 (MacKay, unpublished results, 1999), Morgan, 5 Hanoverian, 8 Tennessee Walking Horse, 8,9 Welsh Pony, 3 Trakehner, 5 Norwegian Fjord, 9 and Andalusian (MacKay, unpublished results, 2001) breeds and in Haflingers 10 and Quarter Horses 11 in Europe. Reported cases in the United States have been from the northeastern, southeastern, midwestern, and northwestern regions, but the condition likely occurs throughout North America. The clinical and histologic changes of EDM are similar to those described by Beech for neuroaxonal dystrophy of Morgan horses. In comparison with the original description of EDM as a degenerative process involving myelin and axons of neurons in the lateral cuneate and thoracic nuclei, the syndrome described in the young Morgan horses was limited to the lateral cuneate nuclei. Other syndromes resembling EDM have been reported as spinal ataxia in captive