Equis ISSN 2398-2977

CNS: myeloencephalopathy - degenerative

Synonym(s): EDM

Contributor(s): Frank Andrews, Caroline Hahn, Robert J MacKay, Michael Porter, Vetstream Ltd

Introduction

  • Progressive degenerative disorder of the central nervous system (CNS).
  • Cause: etiology unknown; vitamin E deficiency has been implicated, along with a familial tendency.
  • Signs: symmetric tetraparesis and ataxia in foals and young horses.
  • Diagnosis: clinical signs and elimination of other neurogenic and neuromuscular syndromes.
  • Treatment: none available. Supplementation of vitamin E may reduce clinical signs but is not curative.
  • Prognosis: progressive condition which may stabilize as animal matures.

Pathogenesis

Etiology

  • Available evidence strongly supports the hypothesis that equine degenerative myeloencephalopathy (EDM) is caused by a vitamin E deficiency that has a familial predisposing component.
  • Other risk factors elucidated include prior use of insecticides and exposure to wood preservatives.
  • Pathophysiology therefore may include exposure to environmental oxidants and lack of antioxidants, including vitamin E.

Specific

  • Access to dirt lots, use of heated pelleted feed and sun-baked forages with low vitamin E contents.
  • Familial tendency.

Pathophysiology

  • Progressive diffuse spinal cord disease   →   tetraparesis and ataxia.
  • Diffuse degenerative disease of the brainstem and spinal cord that affects proprioceptive relay nuclei as well as dorsal and ventral spinocerebellar tracts.

Timecourse

  • Once signs of EDM appear the disease is usually slowly progressive, although some cases may stabilize with maturity.
  • No significant improvement/remission is seen with age.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Nayler R J (2010)Equine degenerative myeloencephalopathy in a horse in the UK.Vet Rec167(10), 380-382 PubMed.
  • Hahn C (2006)The wobbly horse: differential diagnoses.In Pract28(1), 8-13 VetMedResource.
  • Gandini Get al(2004)Equine degenerative myeloencephalopathy in five Quarter Horses: clinical and neuropathological findings.Equine Vet J36(1), 83-85 PubMed.
  • Goehring L Set al(2001)The mystery of equine herpes myeloencephalopathy.Equine Vet Educ13(1), 53-59 VetMedResource.
  • Miller M M & Collatos C (1997)Equine degenerative myeloencephalopathy.Vet Clin North Am Equine Pract13(1), 43-52 PubMed.
  • Mayhew I G, Brown C Met al(1987)Equine degenerative myeloencephalopathy; A vitamin E deficiency which may be familial.J Vet Intern Med1(1), 45-50 PubMed.
  • Beech J (1987)Equine degenerative myeloencephalopathy.Vet Clin North Am Equine Pract3(2), 379-383 PubMed.


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