Equis ISSN 2398-2977

CNS: myeloencephalopathy - degenerative

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

Treatment

Prevention

Outcomes