Current insights into equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy.

The research article discusses equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM), an inherited neurodegenerative disease in horses linked to vitamin E deficiency during the first year of life. Current prevention methods and ongoing research into disease testing and diagnosis are also discussed.

Disease overview

• Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disease that horses inherit and are most likely to develop during their first year of life if they suffer from a vitamin E deficiency. This condition is the second most common reason for horses who showed spinal ataxia to be euthanized due to neurological disease.

Characteristics and Diagnosis

• The eNAD/EDM disease possesses a few identifiable characteristics that primarily include sudden neurologic signs. Horses with eNAD/EDM would often exhibit symmetric ataxia, have a wide-based stance even when at rest, and exhibit proprioceptive defects. Despite these characteristics, there are no known antemortem tests for this disease yet in any horse breed.
• As of now, a confirmed diagnosis for eNAD/EDM can only be obtained after a horse’s death, through a histologic evaluation of the horse’s brainstem and spinal cord at necropsy.

Research and Potential Testing

• Research is actively ongoing in this field to find antemortem biomarker and genetic testing techniques. There is a wide interest in the development of a genetic test for eNAD/EDM, even if such a test were only effective for specific breeds. The availability of such a test could significantly impact the global equine community.

Prevention

• Since no antemortem tests or treatments for eNAD/EDM currently exist, the best approach to counteract this disease is by preventive measures. Pregnant mares and foals should be allowed access to pasture or provided with a diet that includes high doses of the water-soluble vitamin RRR-α-tocopherol, especially during the dam’s last trimester and through the foal’s first two years of life.
• However, it is crucial to measure a horse’s baseline serum vitamin E levels before providing supplementation because oversupplementation of vitamin E, whilst largely safe, can potentially lead to coagulopathies.