Current insights into equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy.
Authors: Young Amy E, Finno Carrie J
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Equine Neuroaxonal Dystrophy/Equine Degenerative Myeloencephalopathy Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) represents a significant neurodegenerative problem in young horses, ranking as the second most common cause of spinal ataxia in horses euthanised for neurological disease, with cases linked to vitamin E deficiency during the critical first year of life. Young and Finno's 2024 review consolidates current understanding of this inherited condition, which manifests as symmetric proprioceptive ataxia (grade 2/5 or worse) and characteristic wide-based stance at rest. A key limitation in clinical practice remains the absence of reliable antemortem diagnostic tests across any breed; conclusive diagnosis currently demands postmortem histological examination of brainstem and spinal cord tissue, though research into biomarkers and genetic testing continues. Prevention strategies should prioritise pasture access for pregnant mares and foals, or alternatively, pregnant mares require high-dose water-soluble RRR-α-tocopherol supplementation during the final trimester followed by continued foal supplementation through two years of age, provided baseline serum vitamin E levels are established beforehand to avoid the risk of vitamin E toxicity and associated coagulopathies. For equine professionals involved in preventative health management, the development of breed-specific genetic tests could substantially alter management protocols, but until such tools become available, careful vitamin E assessment and strategic supplementation remain the most practical defence against this debilitating condition.
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Practical Takeaways
- •Ensure pregnant mares have pasture access or supplement with high-dose water-soluble vitamin E in the last trimester, continuing supplementation in foals through age 2 years
- •Measure baseline serum vitamin E levels before starting supplementation to avoid oversupplementation-related coagulopathies
- •Recognize symmetric proprioceptive ataxia with wide-base stance in young horses as a clinical red flag, though definitive diagnosis currently requires necropsy examination of brainstem and spinal cord
Key Findings
- •eNAD/EDM is the second most common cause of spinal ataxia in euthanized horses with neurologic disease
- •The disease is characterized by symmetric proprioceptive ataxia (>grade 2/5) and wide-base stance, occurring in the first year of life
- •No antemortem diagnostic tests currently exist for eNAD/EDM in any breed; diagnosis requires postmortem histologic evaluation
- •Prevention through pasture access or maternal/foal vitamin E supplementation (RRR-α-tocopherol) is the primary management strategy, with baseline serum vitamin E measurement recommended before supplementation